The invention relates to a debugging platform of a circuit breaker, which comprises a signal generating device and a power supply unit. The signal generating device is used for simulating the power grid and the environment so as to generate corresponding electrical signals and ambient signals. The signal generating device is correspondingly connected with the collecting signal input port of a circuit breaker. The output of the power supply unit is connected with the power supply end of the circuit breaker. The circuit breaker correspondingly conducts debugging actions according to coherent signals generated by the signal generating device. By means of a test platform, the operating environment for the circuit breaker having the phase-selecting and switching-closing function during the running process of the power system can be simulated. The predelivery test workload and the field debugging workload for the phase-selecting and switching-closing type circuit breaker are lowered to the greatest extent. The production efficiency, the operation security and the operation reliability are improved.