The quality of construction relates closely to people's livelihood, and the failure or success depends largely on the main contractor.Recently, the majority of construction units use bidding mechanism to choose the final bidder in construction industry.Therefore, how to evaluate and filter the best bidder is the great challenge faced by the bidding unit.Given the shortcomings in the field of evaluation methods currently and based on the system of evaluation indexes which indicate the bidding characteristics of construction and the weights decided by subjective weighing method and objective weighing method, this article sets up the index weight tradeoff model using least squares method to weaken the shortcomings caused by simply using subjective weighting method or objective weighing method. Then, considering the difficulty in quantizing the indicators of construction projects and combining the fuzzy comprehensive evaluation model, we can review and evaluate all the bidders.Finally, introducing an example and comparing the evaluation results of the three sorts of evaluation methods, this article thereby validates the significance of this idea and method.