The utility model relates to a detection signal synchronizer for a transformer partial-discharge test, which is mainly characterized by comprising a sliding transformer, a voltmeter, an excitation-variable wire connector and a partial tester wire connector. One side of the sliding transformer is connected with the low-voltage side of a to-be-tested transformer through the excitation-variable wire connector. The other side of the sliding transformer is connected with the synchronizing end of a partial discharge tester through the partial tester wire connector. The voltmeter is connected in parallel with the synchronizing end of the partial discharge tester and is used for monitoring the voltage condition of the partial discharge tester. The partial discharge tester is connected with the bushing tap of the to-be-tested transformer. According to the technical scheme of the utility model, the detection signal synchronizer is reasonable in design. Based on the voltage indication of the voltmeter, the voltage applied on the excitation-variable side can be adjusted by the sliding transformer, so that the sampling problem of a synchronizing voltage can be solved. The voltage applied on the excitation-variable side is enabled to be synchronized with a test voltage. Meanwhile, the detection signal synchronizer plays an important role in screening transformer partial-discharge signals. The detection signal synchronizer also has the advantages of simple structure, safety, reliability, convenient usage and the like.