Different grounding modes in low-voltage microgrid bring a series of security and stability issues. To solve these problems, a grounding arrangement for low-voltage microgrid is proposed. With deeply researching national standards and electric standards, combined with the analysis of theory and application, the grounding modes of the main transformation, distributed generation and low-voltage microgrid system are compared respectively, and applicable condition and occasion of various grounding modes in different circumstances are given. Finally, grounding arrangement in the classical microgrid is given by contacting with character of the microgrid, i.e. the main transformer selects D, yn11 connecting group grade preferentially with neutral grounding. The neutral points of distributed generations are ungrounded when microgrid is on-grid, and only the neutral point of main distributed generation turn into grounded when microgrid is off-grid. The whole microgrid system adopts mixed grounding mode with TN-S, TN-C-S and TT by applying four-grade switch for distributed generations and three phase loads and two-grade switch for single phase loads.