The invention provides a power-flow current breaking capacity test synthetic circuit synchronous control device and method. The device comprises a power frequency oscillation circuit as well as a power frequency oscillation startup detection unit, a trigger phase control unit and a photoelectric conversion and ignition unit connected in sequence. The device and the method can avoid the problem of time delay caused by detecting a switch-on contact or circuit current signal, improve the accuracy of time control, reduce electromagnetic coupling interference of self circuit, effectively avoid spatial electromagnetic coupling interference and conducted interference intrusion of a power supply line, ensure safe and reliable operation of the circuit, effectively avoid false triggering accidents caused by high-current electromagnetic interference at the moment of power frequency startup and shock ignition of a system and strong electromagnetic pulse spatial coupling, and improve the running reliability and safety of the system.