The resource-constrained project scheduling problem (RCPSP) is one of the most representative project scheduling problems. In this paper, a project scheduling optimization model based on a generalized resource calendar constraint with resource inputs as variables is established to address the necessity of considering resource inputs in practical situations. Firstly, this paper introduces the concept of combined precedence relationships to integrate and improve the concept and content of the generalized resource calendar. In order to avoid the drawbacks such as network loops that occur in the traditional network diagram when representing combined precedence relationships, the instantaneous state improvement node network diagram with nodes indicating the start and end of activities is used; Second, considering the activity priority relationship, activity duration, total non-renewable resources and resource calendar constraints, and the CP optimizer is used to solve the multi-objective optimization model established in this paper, with the shortest project duration and the smallest project cost as the optimization objectives. Finally, the accuracy and efficiency of the model are verified by designing simulation cases and conducting numerical experiments.