Traditional household DC microgrid operation strategy cannot meet the demand of distributed electricity trading for microgrid users. Therefore this paper proposes a hierarchical control strategy for DC microgrid bus voltages for distributed electricity trading. Under this strategy, the microgrid is divided into six operational areas according to the DC bus voltage signal. According to the characteristics of each layer area, the distributed units in the microgrid are set as a specific voltage master control unit (device objects that control the DC bus voltage) and energy unit (device objects that provide power output). The distributed units change operation mode according to the change of the operational area of the microgrid. Considering the possibility of users' photovoltaic and energy storage resources participating in the trading, based on the microgrid trading model, this paper proposes a control strategy of the microgrid in the state of power sale and power purchase. The simulation results verify the feasibility and correctness of the proposed strategy. This work is supported by the National Key Research and Development Program of China (No. 2018YFB0905000), the Science and Technology Project of the Headquarters of State Grid Corporation of China (No. SGTJDK00DWJS1800232), and the Cooperation Program of UNiLAB-DEM.