Abstract: In order to scientifically evaluate the coordination degree of "water resources-economy-society-aquatic ecosystem" in Yunnan from 2006 to 2016, we introduced YYPO algorithm, projection pursuit (PP) and cloud model (CM) to construct YYPO-PP-CM water resources-economic-social-aquatic ecological coordination degree evaluation model. Twenty indicators were selected from water resources, economy, society and aquatic ecosystem to construct an index system and grading standard. CM forward generator was used to calculate membership of each grade of evaluation index. Eight standard test functions were chosen to verify the optimization performance of YYPO algorithm, and compared it with the performance of other four traditional optimization algorithms including PSO algorithm and CS algorithm. Based on the principle of PP, we employed data from the system to construct PP optimized objective function; the weight of each evaluation index was given by YYPO-PP, grading degree was calculated and analyzed according to membership matrix and weight matrix, and the result was compared to that of the PP method and fuzzy evaluation method. The results show that:① YYPO is superior than traditional methods such as PSO and CS in accuracy, being good at developing and exploring balance and global extreme optimization. ②Yunnan Province is evaluated as "extremely uncoordinated" in its "water resources-economy-society-aquatic ecosystem" between 2006 and 2007, "Uncoordinated" between 2008 and 2009, "Roughly Coordinated" for 2010, "Coordinated" between 2011 and 2014, and "well coordinated" between 2015 and 2016, which indicated that for the past ten years, its coordination degree was gradually improved. ③ evaluation results were in consistent with the results obtained by PP method and fuzzy evaluation method. ④ YYPO-PP-CM model is a combination of objectivity, fuzziness and randomness, not only can it determine the weight of evaluation indexes, reflecting the qualitative concept for "water resources-economy-society-aquatic ecology" coordination and evaluation grading certainty, but also has certain application value.