Terahertz (THz) waves (0.1 THz ~ 10 THz, 1 THz = 10¹² Hz) locate in the transitional region of the electromagnetic spectrum, between the classical electronics (radio, microwave and millimeter wave) and the photonics (infrared, visible, ultraviolet and x-ray). As a kind of coherent measurement technology in THz frequency range, THz characteristic spectroscopy, with high sensitivity, rapidness and nondestructive testing as well as other unique advantages, has shown an attractive promising application prospect in detection, analysis and identification of biochemical molecules and materials. As the widely used broadband THz wave source, THz Photoconductive Antenna (THz-PCA) can emit broadband THz radiation. Therefore, as one of the promising THz emitters and detectors, THz-PCA has the advantages to overcome the defects confronted by other devices (e.g., low operation frequency, strict working condition and bulk size) and these unique advantages have made THz-PCA become the most commonly utilized THz sources in THz Time-Domain Spectroscopy (THz-TDS). Although a variety of THz-PCAs are commercially available and become indispensable in many practical applications currently, the insufficient radiation THz power still hinder the further development of THz technologies based on THz-PCA. In order to further promote the research interests of THz-PCA, the working mechanism and some new research progress, technical challenges in the process of practical application and strategies of THz-PCA have to be discussed and analyzed. The underlying physical mechanism of the transient response in THz-PCA emitter and detector are investigated, as well as the influence of several parameters including the power intensity of femtosecond pump laser, the laser pulse duration and the carrier lifetime of the substrate material, are also analyzed based on theoretical models, which provide the technical foundation for designing the efficient THz-PCA. Moreover, a plenty of valuable research schemes have been proposed to develop the THz technologies based on THz-PCA in the past decades, including photoconductive materials and structure design of THz-PCA. To be specific, the sub-picosecond carrier life time of photoconductor can be realized by creating a massive density of defects, dislocations and scattering centers in the substrate material. As for structure design of THz-PCA, the previous researches on THz-PCA was mainly focused on the saturation effect at high pump power and the large aperture dipoles, dipole arrays and interdigitated electrodes structures have been investigated during the early stage. In the recent years, as the quick development of micro-nano fabrication technologies, the THz-PCA incorporated with plasmonic nanostructures and all-dielectric nanostructures have also been widely investigated for improving its performances.In this paper, the working principle and development status of THz-PCAs based on ultrashort pulsed laser are introduced, including theoretical models, substrate materials and different structures of photoconductive antennas. Furthermore, with the dramatic development of source and detector components, THz spectroscopy technology has been utilized in various fields such as chemical detection and substance identification, biomedical application and pharmaceutical industry. THz-TDS is the most commonly used technique in current commercial THz spectroscopy, which has attracted wide attention for its spectral fingerprint, high temporal-spatial resolution, noninvasive and nonionizing properties. Various important biomolecules, such as amino acids, nucleobases and saccharides reveal rich absorption features in THz range. It is verified that THz spectral features originate from the collective molecules of low frequency vibration, rotation and weak interaction with the surrounding molecules (hydrogen bonding, van der Waals force, etc.), so they are very sensitive to the molecular structure and surrounding environment. It is a powerful tool to investigate molecular conformation, positional isomerism of functional groups, intermolecular interactions of organic acids and their salts, optical isomerism, etc. However, it is worth noting that the investigated targets are usually in the form of multi-component mixtures in actual scenario. When the spectral features became more complicated, the much broader THz features would be severely overlapped and accompanied by baseline drift in THz spectra. Identification and quantitative analysis of complex multi-component mixtures will become a great challenge for THz spectral analysis. To overcome such problem, a practical strategy has been proposed by combining machine learning methods with THz-TDS for implementation of practical applications. Moreover, another issue worth noting is conventional free-standing spectroscopy measurement devices are hardly adequate for the detection of microgram level or trace substance. Combination of metamaterials and conventional free-standing THz spectroscopy to enhance the sensing signal is a feasible and effective method, which is crucial for the practicability of clinical adoption. Furthermore, some recent progress we have achieved in THz characteristic spectral technology and its applications are also summarized and discussed.