The study aimed to investigate the effect of ratios of marrow cavity diameter to intramedullary nail diameter from different layers on hidden blood loss (HBL), overt blood loss (OBL) and total blood loss (TBL) during using proximal femoral nail antirotation-Asian version (PFNA)-II for femoral intertrochanteric fractures.We retrospectively studied 70 patients treated in our hospital recently. We recorded postoperative hematocrit (Hct) and OBL during operation. TBL and HBL were calculated using CROSS equation. The ratios of marrow cavity diameter to intramedullary nail diameter from different layers, including start of funnel, end of funnel and femoral isthmus, were measured. The mean of the ratio from frontal and lateral X-ray were designated as R. We classified all included participants into a high and a low matching group according to z-score of R within each layer. TBL, HBL, and OBL were compared between the 2 groups. We applied multiple linear regression analysis between the HBL as a dependent variable and gender, age, body mass index, fracture type, and R as independent variables.The present study indicated a significant reduction in the HBL and TBL in the high matching group compared to low matching group on three layers, whereas it showed no significant difference in OBL between the 2 groups on three layers. It showed that R values from start of funnel and end of funnel were significantly associated with HBL.Matching rate of PFNA II at the funnel might be an important factor for HBL and TBL postoperatively.