The power supply mode of closed-loop design and open-loop operation is usually adopted in the distribution network. In the actual power grid, the voltage amplitude difference and phase difference of the loop closing point of two transmission lines are often large. If the switch is directly switched on or off, it will bring large opening/closing shock. In serious cases, it will even lead to misoperation of the protection device and overcurrent of the transmission line, which will affect the safe and stable operation of the distribution network. In this paper, a loop closing control device and its control method for 10 kV distribution network are proposed. The phase shifting transformer and voltage regulating transformer are combined to adjust the voltage amplitude and phase of the loop closing point, so as to meet the technical requirements of no impact closing and low current opening in the process of line exit from maintenance and entry after maintenance of distribution network. Besides, the offline simulation model is built on the PSCAD/EMTDC simulation platform, and the detailed simulation test is carried out on the process of line maintenance exit and post-maintenance entry. Moreover, the hardware in-loop test platform of the RTDS with control device prototype is built. The test results show that the distribution network loop closing control device and its control method proposed in this paper can smoothly complete the maintenance exit and post-maintenance entry of the line, the simulink results of PSCAD are consistent with those of RTDS.