Integration of electric vehicles (EV) will introduce a new bottleneck for power supply into distribution network and lower the load supply capability. The evaluation index system for dynamic power supply capability is proposed to depict the sequential dynamic behaviors and the static cross-section characteristics respectively, and quantitate the power supply capability from the system level and components level separately. On this basis, an optimization model targeting to improve the maximum power supply capability is formed, which lead the dynamic behavior of newly added load and EV charging load to enhance the power supply capability by the means of network reconfiguration and demand response. Successively, some nonlinear processing technologies such as second-order cone programming and big-M method, will be taken to transform the original model into a mixed integer second-order cone programming model which will be solved by CPLEX efficiently. Finally, case studies on the modified IEEE 33 buses system demonstrate that the proposal will improve the load supply capability and load equilibrium simultaneously.