An active/standby switchover device and an active/standby switchover method of an asynchronous backplane in a transport network are provided. A local oscillator clock is adopted to obtain a clock of a working path, so as to replace the clock of the working path tracked in a phase-locked loop mode. An active/standby switchover operation is realized by using the local oscillator clock, so that the implementation cost is greatly reduced, and the hysteresis problem of the phase-locked loop tracking clock during the active/standby clock switchover is eliminated, thereby effectively achieving the lossless switchover of services.