A time synchronization apparatus and method for automatically detecting the asymmetry of an optical fiber. The apparatus comprises an OTDR asymmetry detecting module (12), a time delay compensating module (14) and a time synchronization correcting module (16), the OTDR asymmetry detecting module (12) comprises an emitting unit (122) used for emitting a detection signal to the optical fiber, a receiving unit (124) used for receiving the detection signal returned by the optical fiber, a transmission time delay determining unit (126) used for determining the transmission time delay of the detection signal in the optical fiber according to the time difference between the emitting detection signal and the returned detection signal, and the determining transmission time delay of a service signal in the optical fiber according to the transmission time delay of the detection signal; The time delay compensating module (14) is used for calculating asymmetric time delay value between the first optical fiber and the second optical fiber according to the transmission time delay of the first optical fiber and the transmission time delay of the second optical fiber; The time synchronization correcting module (16) is used for synchronization correcting time according to the asymmetry time delay. The apparatus and method can improve the time synchronism precision.