Abstract: For early selection and real-time slaughtering of beef, the ribeye muscle area（EMA）and surface fat between the 12th and 13th ribs over the longissimus muscle（RIB12）of 60 cattles when they were 8 and 22 month old were gotten by live animal ultrasound measures. The cattles were slaughtered after fatten for 14 months. Data of EMA and RIB12 measured by ultrasound system and weight of 50 cattles chosen from 60 cattles in random in 8 and 22 month old were used to establish the forecasting models of EMA, RIB12, high-grade beef, rear beef, fine-quality beef and carcass weight after slaughtered. Forecasting models with the weight data or not were detection analysis. The results show that the deciding coefficients of pos slaughter EMA, RIB12 were less than 0.75, but that of high-grade meat, rear beef, fine-quality beef and carcass weight were over 0.75. The pre slaughter traits and pos slaughter data of other 10 cattles was used to test the forecasting models. The results show that there are no significantly difference between forecasting values and measured ones. It can be concluded that it is feasible that pos slaughter EMA, RIB12 and beef production traits can be forecasted by EMA and RIB12 data measured by ultrasound system and the models with the weight data are more accurately than that without the weight data.