Power system faces thousands of physical and cyber attacks which seriously threaten its security. It is noted that most defense methods are only suitable for specific cyber attacks and are not applicable to physical attacks. This paper provides a generic method regardless of different attack types through topological efforts to reduce potential loss of the power grid. In this paper, a proportional loss model is proposed depending on the different attack-defense resource allocations. The optimal allocation strategy can be converted into the solution to a minmaxminmax problem. In order to further improve the security of the power grid, by taking the geographical feasibility into consideration, a hexagonal construction method is proposed to provide a cost-affordable and geographically-feasible solution for new power grid construction.