Objectives　To study the morphologic features of the proximal femoral medullary cavity, and provide basis for the design and application of the domestic proximal femoral nail(PFNA).    Methods　The CT image data of 120 Chinese proximal femurs（male 55 cases， female 65 cases）were collected in this study. Three-dimensional anatomic parameters, including internal diameter of medullary cavity, and the canal flare index of the proximal femurs, were analyzed adopting mimics software, while, the correlations of the above parameters with the age, the height and the gender of patients were analyzed statistically.  Results　 Using the mid-point of lesser trochanter as a reference，the internal diameter of medullary cavity were  T+20(44.79±5.42)mm and (39.79±4.96) mm；T+10(34.00±3.64) mm and (32.06±3.29) mm；T(26.93±3.71)mm and (24.18±3.31) mm；T-20（(18.65±2.96) mm and (18.21±2.60) mm for male and female respectively, as well as of the isthmic portion (10.40±1.45)mm and  (10.15±1.05) mm respectively. There were significant difference of the above parameters between both sexes in T+20, T+10 and T states (P<0.05), on the contrary, no significance appeared in T-20 and isthmus states. All data were positively correlated with patients' height except for MCFI, which was negative correlated with the height. The internal diameter of the medullary cavity were positively correlated with patients' age (P<0.05), however, there were no correlation between the age and CFI, MCFI and DCFI. Conclusions　The anatomic parameters of medullary cavity are variable for both sexes and different races, which implicates that, it is important to select the suitable fixation devices for treating different intertrochanteric fracture.