To improve the quality and efficiency of femoral stem prosthesis design, a Monte Carlo method based on femoral bone marrow cavity analysis is proposed to measure morphological parameters using anatomical semantics. The region of interest is the femur, which includes the medullary cavity and cortical region. After this region is extracted, the size of the cavity and region is simulated using the Monte Carlo method. Finally, based on clinical needs, the morphological parameters are calculated and analyzed based on the size of the region of interest. From the perspective of the probability model, the non-random problem of solving the cross-section area of the femoral marrow cavity is transformed into one having a random nature so that a probability model can be used. The experimental results show that this method is simple, flexible, and efficient. It provides a new and reasonable scientific method for comprehensively understanding the anatomical morphological changes of the femoral marrow cavity. The measurement and analysis of the morphological parameters of the femoral bone marrow cavity in this paper provide the necessary scientific theoretical support for improved morphologic research, design, and clinical selection of femoral stem prostheses and has important significance and application value in clinical practice.