The networked command information system is the basic support and important hubs for system operations under the conditions of modern informationization. Based on the analysis of the structure and function of the networked command information system, this paper constructs a double layer dependent network with weights, proposes a cascade failure model considering node overload and node repair, and constructs three improved strategies based on the weight-based load redistribution strategy. Taking the "LB manoeuvre" data as a sample, the effects of attack mode, load redistribution strategy and network performance parameters on network invulnerability are studied. The simulation results show that the important nodes of the physical layer are the most critical to the network performance, and the network performance will be abrupt under the deliberate attack. The improved three strategies, especially the comprehensive redistribution strategy, can significantly improve the network invulnerability. And in a certain range, the network invulnerability is greatly improved.