According to the deficiency of wide support calculation methods for crane girder of big pile cap in Design and Construction Code for Open Type Wharf on Piles (JTS 167-1—2018)，this paper puts forward a calculation model of the continuous beam with wide supports considering rotational restraint and derives a formula for rotational stiffness coefficient of wide supports.It programs the finite element program of the model by using Fortran language，establishes the space finite element model of the longitudinal bent through ANSYS software for comparative analysis，and obtains the internal force of the continuous beam under different calculation models.The calculation results show that under the condition of uniformly distributed load，ignoring rotational restraint to a continuous beam with wide supports will produce larger errors in the maximum positive moment，and the maximum positive moment obtained by the model of the continuous beam with wide supports considering rotational restraint agrees well with the space model.The maximum negative moments calculated by the method in the code and the proposed model in this paper both have a larger difference from the space model.Therefore，this paper analyzes the reasons and puts forward suggestions for improvement，so as to provide a reference for similar wharf structure design.