The filtering of ultra-short optical pulse is always a conundrum, and it is difficult for ordinary optical devices to distinguish the picosecond level optical pulses. Based on time lens technology, a filtering system for ultra-short optical pulses is developed. An optical pulse passes through a Fourier transform system which is composed of standard single mode fiber(SSMF) and time lens, and it’s intercepted by an optical switch after Fourier transformation. The truncated pulse passes through an inverse Fourier transformation system composed of time lens and SSMF again, and the filtered waveform is obtained. The experimental results show that the time resolution reaches the picosecond level. The proposed method adopts an all-optical system with simple structure and good real-time performance.