Micro-grid has already been an essential part of smart grid. It is an effective way to connect distributed generation such as renewable energy to power grid. It is most important to evaluate the power quality objectively and professionally for the micro-grid. Based on analyzing the characteristics of micro-grid power quality, this paper proposes a new power quality evaluation method suitable for micro-grid. First of all, from the perspective of voltage, current and frequency, compared with traditional power grid, every index of micro-grid power quality is analyzed in detail and the characteristics of indexes are pointed out. According to some relative standards, all power quality indexes’ thresholds are ensured. Further, based on fuzzy evaluation method, Cauchy distribution membership function is adopted to determine all indexes’ membership belong to the optimization. Indexes’ subjective weights are defined by G1 method. Combined with the subjective and objective weights, the synthetic weights are got and used for comprehensive evaluation. And a quantitative micro-grid power quality evaluation result is obtained. Finally, simulation is applied by a given set of data from micro-grid. Simulation results prove that the proposed method is accurate and effective. This work is supported by National Natural Science Foundation of China (No. 61573155) and the Fundamental Research Funds for the Central Universities of South China University of Technology (No. 2015zm008 and No. 2015zz097).