The invention discloses a method for improving lightning protection performance of an altering/direct current joint circuit. The method includes the steps that supports are arranged on altering current wire cross arms of the single-loop +/- 800 kv and double-loop altering current one-tower multi-loop altering/direct current joint circuit; lightning wires are arranged on lightning wire supports along the altering/direct current joint circuit; bypass ground wires are arranged on supports. By means of the technical scheme, the shielding failure trip-out rate of a 500 kv circuit located at the hilly area is reduced to be lower than 0.14 time/ (100km.a), the shielding failure trip-out rate of a 220 kv circuit is reduced to be lower than 0.315 time/ (100km.a), and the shielding failure trip-out rate of the 500 kv circuit and the shielding failure trip-out rate of the 220 kv circuit are equal to the lightning trip-out rate running value of the 500 kv circuit and the 200 kv circuit.