Abstract: Three techniques for measuring the pulse-to-pulse timing jitter of gainswitching semiconductor laser were experimentally compared. By experimental investigation, the advantages and disadvantages of these three measurement techniques were demonstrated and listed. It is found that the timing jitter measurement technique based on wide-band sampling oscilloscope is suitable for the measurement of the pulses with wide-band and big jitter, the resonance frequency spectrum analysis technique based on frequency spectrograph is applied to the optical pulse measurement of low repetition frequency, and the phase noise measurement technique based on the phase detector is applied to the measurement of high repetition frequency. It is pointed out that the phase noise measurement technique based on the phase detector has the advantages of high measurement accuracy, big dynamic measurement range and credible measurement result.