The invention discloses a testing method of a series compensation protection device. The series compensation protection device comprises a capacitor bank C, a normally open contact GS1, a normally open contact DS1, a normally open contact GS2, a normally open contact DS2, a normally open contact Contact MBS, varistor MOV1, varistor MOV2, damping circuit, spark gap GAP, bypass switch BPS and insulating platform; capacitor bank C includes capacitor C1, capacitor C2, capacitor C3 and capacitor C4, capacitor C1 and capacitor C2 are connected in series, capacitor C2 and capacitor C3 in series, capacitor C3 and capacitor C4 in series, capacitor C4 and capacitor C1 in series; the damping loop includes resistor R1, varistor R2 and inductor L, resistor R1 and varistor R2 in series, varistor R2 and inductor L in series, inductor L in series with resistor R1. The series compensation protection device of the invention ensures the triggering reliability of the spark gap, the continuity of spark gap triggering, the correctness of the action behavior of the spark gap, high trigger reliability, high withstand voltage level and low failure rate.