The application of long-span post-tensioned pre-stressed box track beam in port engineering has a trend of development,but the design requirements of port engineering are not specified in detail,and the research of this structure calculation is still less at present.Combining with the engineering example,according to the port and highway engineering codes and related literatures,we apply the finite element software to numerical simulate and analyze the mechanical property of long-span pre-stressed box track beam,meanwhile we consider the influence of the vertical nonlinear gradient effect on the internal force.This method can reflect the stress and displacement distribution of each part of the component comprehensively and accurately,and the verification result is reliable.