Photonic crystal fiber (PCF) can be designed flexibility. In general, the propagation properties of the PCF are adjusted by changing the sizes, shapes or arrangement of the air holes, and then the PCF with high birefringence, high nonlinearity, flattened dispersion and low confinement loss can be obtained. PCF has potential applications in different fields, such as distributed optical fiber sensor, femtosecond laser, gas sensor and so on. In this paper, firstly, the structure characteristics of PCF and the difference between the traditional singlemode fiber (SMF) and the PCF are introduced. Secondly, their typical structures and propagation properties are analyzed. Thirdly, the sensing mechanisms and performance of distributed optical fiber sensor, femtosecond laser and gas sensor based on the PCF are introduced in detail. The results show that compared with the traditional SMF, the PCF can achieve more excellent performance in applications. Finally, the developments and applications of PCF are summarized and prospected.