Traditionally, bidding theory model its fact is mainly winning the project, investigation the bidding probabilities of the bidding price and to consider, their expected profit value as the reference for bidding. But now the construction market is more competitive than before. So contractors must integrate their viewpoint for strategic bidding. This case study considers the economic environment changes, objectively uses the economic variables and subjectively evaluates the utility function to get the optimal return rate and the bid price at the maximum expected utility increasing under interest rate, inflation rate, reinvestment rate and other economic environment variables, to help decision-makers can make more suited to their own and the most competitive bidding strategy.