At Shanghai Synchrotron Radiation Facility (SSRF)

timing signals are sent via optic fibers from event generator (EVG) to event receiver (EVR) for all kinds of subsystems and equipments to get precise sequence signal. But the phase drift between output signal sent from EVR and high frequency signal is produced for temperature variation of optic fiber caused by complicated local environment. In order to compensating the phase drift

a phase drift compensation system for the timing system has been developed. In this paper

we report in detail the hardware architecture and the digital phase detecting algorithm

and test results of the compensation system as well.