Objective To study the primary stability difference of the trapezoid sleeve combined with different length and shape prosthesis stem by finite element analysis. Methods The finite element model of femur-sleeve-prosthesis was established, the contact mode was set as face-to-face contact, and the micromotion of femur-sleeve-prosthesis stem was studied by simulating the condition ofstanding on one foot and fast walking in physiological activities. Results The micromotion value of trapezoid sleeve combined with straight stem was larger than that of curved under stangding on one foot and fast-walking loading. The peak value and average value of micromotion reached the peak when the length of prosthesis stem was 120mm, the average value of micromotion of trapezoid sleeve combined with straight stem was 67.7 ± 43.5 μm and 64.1 ± 59.2 μm, and the peak value of micromotion was 121 μm and 146 μm.The micromotion value around the trapezoidal sleeve remained constant as the length and shape of the prosthetic stem changed. Conclusion The trapezoidal sleeve combined curved stem is superior to the straight stem and maintains the optimal primary stability when the prosthetic stem length is 90mm.