The invention discloses an automatic adjustment method for a series compensation asymmetrical operation circuit backup zero-sequence protection constant value. The automatic adjustment method comprises the following steps 1, a circuit protection apparatus collects a system operation signal in real time, and judges whether the system enters a series compensation asymmetrical operation state or notin a circuit no-fault condition; and 2, when it is judged that the system enters the series compensation asymmetrical operation state in the circuit no-fault condition, the circuit protection apparatus performs automatic adjustment on the zero-sequence final section protection action constant value so as to adapt the operation state. Preferably, in the step 1, the circuit protection apparatus collects the protection action signal of the circuit, the protection action signal of the other set of dual-configured circuit, a series compensation protection action signal and a series compensation bypass switch position signal in real time. Manual intervention is not needed, and circuit mistake removal caused by inaccurate circuit protection action due to the asymmetrical operation state of seriescompensation can be prevented, and the overall automatic performance of the system is improved and the action performance can be ensured.