It is the key to determine reasonably the internal forces of the lock head for guaranteeing the system stability and safety lock structure，and it’s an important basis for the reinforcement design as well.The large-scale finite element analysis softeware ABAQUS is used to develop a three-dimensional finite element model of the lock head in a ship lock and the simulation scale of foundation.The model can be used to analyze the stress distribution and deformation characteristics under different working conditions.We compile the calculation procedure to get the internal force by the stress，and achieve the internal force distribution of each control point，which is compared with that by the standard algorithm.The results show that the canonical algorithm is conservative，while the finite element method considering the overall deformation and displacement，internal force calculation of large lock head is more consistent with the actual stress.