Previous researches on cascading failure of interdependent networks are based on the same subnet cascade mechanism. Based on the previous studies, the loadcapacity model is used to propose a cascading model based on different subnet cascade mechanism. The impact of different attack strategies on the robustness of interdependent network is analyzed. By simulating interdependent ER random networks and interdependent scalefree networks, the effect of different attack strategies is compared, and the influence of topology elements on different tactics is found. In addition, by analyzing the results of different cascading failure mechanisms under the same attack strategy, it is discovered that the symmetry of the cascading failure mechanism greatly affects the robustness of interdependent network.