VSC-HVDC can improve the stability of AC grid, but the electronic equipment also changes the AC fault characteristics, so it is necessary to re-verify the AC line protection connected with DC system. Based on the different operation modes of VSC-HVDC, the fault characteristics on DC side are analyzed. The magnitude of positive and negative sequence fault current is greatly influenced by DC control strategy and the negative sequence fault current is completely suppressed, but the zero sequence fault current characteristics are not affected. The analysis of the AC fault traversal strategy of the project shows that the active current limiting link during the fault crossing is the main reason that affects the magnitude of the soft-side fault current. Aiming at the fault characteristics, an optimization strategy of starting elements is proposed, which is based on AC strong fault side commanding VSC-HVDC weak fault side and voltage reduction criterion. Finally, a simulation model is built in PASCAD/EMTDC software and the effectiveness of the proposed optimization strategy is verified. This work is supported by Science and Technology Project of State Grid Central China Division (No. SGHZ0000DKJS1800142).