A feeder reconfiguration method is presented with the aim of decreasing network losses subject to branch flow limits, voltage limits and protection triggering limits to optimize the selection of breakers for loop closing and opening operation at the 10 kV distribution network. An improved genetic algorithm with binary chromosome encoding for breaker status is used. A chromosome library with feature encoding is created according to the calculation results for closed loop network to accelerate the algorithm process. A distribution coefficient method is used to calculate the power flow for open loop network based on the closed loop network to avoid extra power flow calculation. A study case demonstrates the effectiveness and correctness of the method which secures the loop closing operation for distribution network. This work is supported by National Key Research and Development Program of China (No. 2016YFB0900200).