The spatial resolution, sensing distance, measurement accuracy and measurement time of the Brillouin optical time-domain analyzer (BOTDA) are interrelated to each other. How to improve the performance of the BOTDA system has been a hot topic in the field of distributed optical fiber sensing. Because the sensing distance and measurement accuracy of the BOTDA system are closely related to the signal-to-noise ratio (SNR), the performance enhancement of the system focuses on the improvement of the SNR and the spatial resolution. The technical methods to improve the performance of the BOTDA system are reviewed. These technologies have extended the sensing distance and improved the measurement accuracy of the system, which make the BOTDA system more suitable for the practical engineering. After analyzing the existing problems, the future research directions are prospected as well.