Considering the issue of objective weight overwhelming subjective weight when the subjective weight and objective weight is inconsistent in multi-index evaluation problem, based on G1 method and the objective weighting method, an assembled weighting model combined with G1 method improved by composite power function was proposed. Firstly, an index system was built, and the subjective ranking and subjective initial vector were determined by G1 method. Thus, each objective index vector was calculated by objective weighting method. Secondly, without changing the ranking order, the comprehensive weights integrated with both subjective and objective components were obtained by utilizing composite power function. Lastly, comprehensive evaluation was calculated by using standardized values of indices and comprehensive weights. Merchants data crawled from Dianping.com was adopted for the experiments of comprehensive evaluation. The Root-Mean-Square Error (RMSE) of the new model was 3.891, which is lower than the result of 8.818 obtained by the G1-entropy weighting and the result of 4.752 obtained by the standard deviation improved G1. Meanwhile, the coverage rate obtained by the new model was better than the two baseline models as well. On the other hand, the RMSE obtained by changing subjective ranking order is 5.430, which is higher than the result of 1.17 that obtained by changing subjective initial vector. The experimental results demonstrate that the evaluation values obtained by the new model highly match with the counterparts given by the Dianping.com, and the model can significantly weaken the effect of initial subjective values, which reflects the fundamental status of the subjective ranking.