Abstract: In this paper, the precision delay generator with closed-loop monitoring of synchronous timing is developed. To enhance the anti-interference ability of signal transmission, the output of the delay generator is transmitted with optical signals. The optical synchronization signals is transmitted and fed back by using single-fiber feedback optical module. Based on the interpolation time interval measurement method, the time difference between the feedback optical synchronization signal and the reference signal can be measured with high precision. This system realizes the timing closed-loop monitoring of optical synchronization signals, and the error is less than or equal to 250 ps. On the one hand, the precision delay generator can ensure the reliable delivery of the synchronization signal to the trigger object. On the other hand, the inherent delay of the synchronization signal through the light transmission can be obtained according to the compared result between measured time difference and the set timing delay, so as to meet the precise configuration requirements of the precision timing.