In order to encourage general contractors to take full advantages of the integration of DB (design-build), effectively respond to the risk of engineering quantity, and create added value for hydraulic projects under general contracting, benefits should be shared rationally by all parties involved. Based on the target cost contract, we use bargaining game model and prospect value theory to construct a value-added sharing model under the bounded rational decision-making of owners and general contractors, and uses numerical analysis to observe the influence mechanism between parameters. Results show that the value-added sharing coefficient, which is obtained using the prospect value as the basis and bargaining game as the method for decision-making, is greatly affected by the reference point and owner’s negotiating loss coefficient. Moreover, the reference point is further affected by the contribution degree of general contractor’s capacity and effort input to the value-adding of the project. In the actual engineering practice, the value-added sharing coefficient can be obtained by setting information sharing channel and the order of the arranged decisions for the rational allocation of the added value. The research results can not only provide some effective guidance for the practice of value-added sharing, but also shed some light on the application of general contracting mode in hydraulic engineering projects.