When multi-level locks overhauling，we need to make filling or draining water process in advance.The current manual calculation takes time and energy,and unable to calculate the optimal solution.At the same time,manual calculation will be more inadequate when some parameters or conditions are changed impromptu.According to that,we design the automatic algorithm of filling or draining water process and the algorithm of process optimization,by which we develop the ancillary software of make filling or draining when overhauling.The algorithm is logically correct and reasonable,and has effective boundary conditions.The test results show that the algorithm can calculate the possible filling or draining water process,and also can optimize process.We can quickly correct processes by the software when conditions change impromptu.