To simulate the shape of the pipe and cable in the initial pipe laying operation accurately, a realistic virtual training environment of pipe-laying operation was created. For the initial S-laying and based on the Euler-Bernoulli beam theory, the geometric nonlinear differential equations is established by analyzing the static force of initial pipe laying and cable. To solve the problem of the differential equations boundary conditions, an iterative method based on differential quadrature method is proposed. By simulation and experiments, the shape and variation of the internal force of the pipe and cable under different operating conditions are analyzed, and the accuracy of the algorithm for initial S-laying is proved. The practical example shows that the algorithm can be applied to the initial S-laying effectively. The accuracy of the differential equation is improved and it is easy to be programmed by using this method, which contributes to the preview of offshore pipe laying operation , feasibility analysis and optimization of operation plan.