A method for synchronizing list-mode data of single events in a PET imaging includes: acquiring list-mode data of single events of each independent detector module, calculating a probability density of time intervals between occurrences of single events in detector module and setting initial parameters, determining detection starting time difference of each detector module with iterative peak searching and graded time window, and performing synchronization correction and coincidence discrimination on the single event data in each detector module based on the detection starting time difference. A system for synchronizing list-mode data of single events in a PET imaging includes: a data acquisition and frequency difference compensation module, an initial parameter setting module, a coarse time scale coincidence module, a fine time scale coincidence module and a data synchronization correction and coincidence discrimination module.