Abstract: The rolling force in strip rolling process was solved nonlinearly by the program we developed via the 2D compressible rigid plastic FEM. With the aim of keeping the calculation accuracy unchanged and shortening calculating time, the influence of initial velocity field on calculating time and calculated results were discussed, where the initial velocity field was set differently by the primary, G function or improved refined mesh methods. It was founded that the calculated values of rolling force conform well to the measured values and meet the required accuracy. The relative calculation error can be controlled within 3% by any of the three methods. The initial velocity field affects little the solution to rolling force. In comparison with the primary method, the iteration steps in the G function and improved refined mesh methods are fewer. Because solving the equation sets is necessary, the time required for calculating the initial velocity field set by G function method is the longest one. As to the initial velocity field set by the improved refined mesh method, the calculating time is shortened due to decreased iteration steps with calculation accuracy unchanged, thus improving the calculation efficiency and solution stability.