Aim\ To develop the software of 3 D displacement field during solidification of steel castings. Methods\ The unknown displacement is solved by applying the nonlinear finite element analysis and stiffness increment variation method. Results\ The program has been applied to simulate the displacement field during solidification process of steel castings and well satisfactory results have been achieved. Conclusion\ This analysis is the basis of the simulation of stress field and the prediction of hot tearing during solidification of steel castings.