Aiming at solving the limitations of current green construction water saving measures, a comprehensive evaluation method for green construction water saving measures based on combined weight-vector angle cosine model is proposed. First, in view of the lack of macro-efficiency evaluation of water-saving measures in green construction, we chose to proceed from the perspective of the comprehensive benefits (i.e. social, economic, ecological, and technological benefits) of water-saving measures, and established a sound evaluation index system for comprehensive benefits of water-saving measures. Then, the comprehensive benefit of water-saving measures was evaluated using the combination weight-vector angle cosine method, which can not only reduce the influence of subjective and objective factors on the evaluation results, but also save water according to the distribution deviation degree of the sample weighted eigenvalue matrix. Measures to directly make objective evaluations and decisions have greatly improved the efficiency of decision-making. Finally, we evaluated the comprehensive benefits of five water-saving measures in a published literature, and the results of the evaluation were compared with that of the TOPSIS-entropy-weighted decision-making method, and we found that the two results are in good agreement with each other, This study proved the reliability of the new method and provided guidance for the decision-makers to choose efficient water-saving measures according to local conditions.