False data injection (FDI) attack is one of the attacks that can seriously affect the operation of power systems. Some studies have focused on the cyber-attack methods of AC-DC hybrid systems. However,few studies pay their efforts on the optimization of FDI attack on AC-DC hybrid systems. Therefore,an FDI attack strategy optimization method for AC-DC hybrid systems is proposed in the paper. Firstly,a two-layer optimization model with the objective of maximizing the loss of FDI attacks is established. In the upper model,the attacker launches FDI attack on the measuring system to find the optimal attack strategy to maximize the economic loss of the power system. The lower layer model calculates the maximum economic loss under a FDI attack with the objective of minimizing the generator output adjustment and load shedding，considering the security constraint of AD-DC hybrid system and the risk of commutate failure of DC converter station. Then,the two-layer optimization model is solved by the genetic algorithm to generate the optimal attack strategy. Finally,the improved IEEE 14-bus system is taken as an example to verify the effectiveness of the model. Simulation results show that the attack strategy optimized by the proposed method can effectively improve the cost of security constrained economic dispatch (SCED).