Abstract: Main network and microgrid can be supported by each other when microgrid is grid\|connected, which can improve operation level, safety and stability. In microgrid standard system, grid\|connected standard should be the most important and be preferentially considered. In this paper, according to comprehensive analysis of microgtid operation, some factors should be considered when determining voltage grade of microgrid. Factors include microgrid capacity, microgrid type, capacity and access mode of DGs, proper injecting current and voltage range at PCC (Point of Common Coupling). Then, issues, such as characteristics of microgrid and its impacts on power quality of distribution network, are fully considered, and some factors that should be considered when determining voltage grade of distribution network connected to microgrid are obtained. The factors include impacts of EVs access on PCC, voltage variants at PCC during power factor and system operation mode change (by using of BPA simulation), etc.