False data injection attack is one of the important factors that threaten the safe and stable operation of power systems. The research on the methods of the attack against power systems can provide decision-making basis for the improvement of power system defense measures. Considering the operation characteristics of high voltage direct current (HVDC) converter station and AC-DC coupling characteristics, a false data injection attack method for AC-DC hybrid system is proposed. Firstly, the basic principle of state estimation of AC-DC hybrid systems is analyzed. Secondly, the attack strategy in AC-DC hybrid systems is proposed, and the attack model is constructed. Finally, the improved IEEE 30-bus system is taken as an example for simulation verification. The results show that the false data injection attack against AC-DC hybrid system can bypass the bad data detection algorithm and endanger the safe and stable operation of the system, which verifies the effectiveness of the proposed model and method.