Tender offer is very important to the construction enterprises in the bidding process. So how to identify the individual cost objectively and efficiently is studied in the essay. The relations of social average cost and individual cost, the factors affecting the individual cost and the difficulty in ascertaining the cost in the bidding process are analyzed. Grey RBF neural network model is built combining with the cost index to obtain the social average cost. The Analytic Hierarchy Process model is made to analyze the rate of each factor affecting the individual cost through expert system. On the basis of the social average cost combining with the affecting rate of each factor, the individual cost could be judged. This method is of practical significance and proved effective through a living example. The conclusion could provide reference for construction enterprise to select the bidding strategy.