According to the limitless of weighting according to the subjective principle or the objective principle and their combination， and to make the comprehensive evaluation more scientific， an integrated weighting method taking into account both the objective and subjective influencing factors is studied and presented. This method takes the decision-makers subjective weights and objective weights as the standard， and the minimum sum between the integration weights and subjective and objective weights as the object. With the optimal combination model created on the moment estimation theory， the optimal combination weights can be arrived at by finding the best solution of the optimal combination model. On this basis， by referring to the grey relational degree， the grey comprehensive evaluation method of power quality based on the optimal combination weights is developed. The power quality of 10 kV buses in the regional power grid is evaluated with the grey comprehensive evaluation method. The evaluation results not only verify the reasonability of the proposed integrated weight method， but also show the validity of the grey comprehensive evaluation method for power quality.