Phase-sensitive optical time domain reflectometer is a distributed optical fiber sensor, which has the characteristics of electromagnetic interference resistance, corrosion resistance, low loss, high precision and wide detection range. It is widely used in monitoring oil and gas pipelines, detecting intrusion, fault diagnosis of transmission lines and seismic wave detection. However, real-time processing of a large amount of data generated by these sensors brings great challenges. Aiming at the problem that the amount of data is too large to be processed in real time, a real-time processing technology of distributed optical fiber sensing signal based on FPGA is proposed. By downsampling technology, the data volume is reduced. Through the improved unwrapping algorithm, the limitation that the frequency should be less than one sixth of the sampling rate in differential expansion is eliminated, so that the algorithm can be applied to high-frequency vibration signals. The improved coherent fading suppression algorithm is used to eliminate the wrong phase, which reduces the hardware requirements and enables the algorithm to be applied to real-time data processing. The experimental results show that the sampling rate of this technology is 62.5 MHz, the response time is 0.5 s, the spatial resolution is adjustable between 4.8 and 20 m, and the sensing distance is adjustable between 1 and 20 km. The real-time processing technology of distributed optical fiber sensing signal based on FPGA can further promote the application and development of distributed optical fiber sensing technology.