The floor, which belongs to the typical space force structure, is the most complex part of the lock head. At present, the elasticity beam method is still the main method in the code for the internal force calculation of the lock head floor. Being the plane calculation theory, this method replaces the elastoplastic with elastic, so it can be optimized. According to the shiplock project in the soil base, using the finite element software ANSYS, nonlinear finite element analysis of three dimensional based on Drucker-Prager criterion, we analyze the lock head floor of shiplock based on the elastoplastic model, compare it with the elasticity beam and elasticity finite element method, and analyze the applicable conditions of various methods, to provide reference for similar shiplocks’ engineering.