In order to select and determine the DC microgrid voltage level, on the basis of the voltage level for existed DC standards and DC projects, considering the capacity and power supply radius of the microgrid, this paper calculates run loss of the DC microgrid to select the optimal voltage level of the DC bus. For the voltage stability control of DC microgrid, in grid-connected operation, the battery DC/DC converter is used to control the voltage stability of DC bus, and the AC/DC converter is used to control the grid power of DC microgrid. In islanded operation, the battery DC/DC converter is used to control the voltage stability of DC bus, too. The simulation model of DC microgrid in PSCAD/EMTDC is established to verify the voltage stability control strategy on different operation modes. The results show that the control strategy can control DC microgrid voltage stability in the case of PV power and load power fluctuations. This work is supported by Key Special Project of Smart Grid Technology and Equipment of National Key R & D Plan (No. 2016YFB0900601).