Taking cash flow balance as the objective，this paper studies the project scheduling problem under different payment conditions． Based on the identification of the studied problem，the authors construct the optimization model under the milestone event payment condition and then extend it to the cumulative time，cumu-lative earned value，and cumulative expense payment conditions． Because of the strong NP-hardness of the problem，a tabu search heuristic algorithm is developed． The algorithm is tested and compared with other two heuristic algorithms on a data set generated randomly． Ultimately，an example is used to illustrate the method and the influences of the payment conditions on the objective of cash flow balance are analyzed． The conclusions are as follows: Payment conditions may exert an important influence on cash flow balance，and with the increase of payment number，payment proportion，and project deadline，it becomes easier for contractor to balance cash outflows and inflows．