The injections of distributed generation make distribution network reconfiguration need to consider more security. In this paper, an network reconfiguration with the lowest active power loss in the reconstruction period and the network operation safety as the constraint is established in distribution networks based on the distflow equations. In order to solve the proposed mathematical model effectively, the convex relaxation method is used to relax the quadratic terms into mixed integer second-order cone programming form, and then the proposed mathematical model of network reconfiguration could be solved using YALMIP effectively. Finally, the feasibility and effectiveness of the proposed network reconfiguration is verified via the modified IEEE 33-bus test system, and the simulation results show that the proposed reconfiguration based on convex optimization is better in global optimization ability, algorithm stability and computation efficiency than that based on particle swarm optimization (PSO) and other heuristic algorithms.