[Objectives] In the research of automatic forming of ship bidirectional curvature plate, the calculation accuracy and efficiency of strain distribution is an important issue. In view of the limitations of the existing methods of calculating strain, a method is proposed to improve the calculation accuracy of the strain distribution of ship bidirectional curvature plate, and the proposed method has high calculation efficiency, which meets the needs of engineering application. [Methods] Taking the circular flat plate as the research object, the secondary development of the subroutine in the finite element software is carried out, and the displacement field load is gradually applied, which improves the calculation accuracy of the strain distribution. Considering that the actual machining process is an elastoplastic deformation process, the influence of material nonlinearity on strain distribution is discussed. From the perspective of calculation accuracy and calculation efficiency, the applicability of various calculation methods is discussed. [Results] The calculation method using subroutine solves the problems of insufficient precision, complex modeling and low calculation efficiency of the existing methods. From the perspective of calculation efficiency, it is recommended to use the elastic large deformation finite element method to calculate the strain. For the target shape with different curvature radii, some reasonable suggestions are given for the selection of calculation methods. [Conclusions] The research results can quickly provide accurate strain distribution for the automatic forming system of the ship bidirectional curvature plate, which has practical engineering application value.