Abstract: In the trial,ninty three-way cross [Duroc×（Landrace×Yorkshire）] pigs with body weighing of 31 kg were assigned into three treatments based on the feature of weight and sex,and they were fed with the different levels of protein diets respectively.The protein content of growing pigs diets among control group,treatmentⅠand treatment Ⅱ was 17%,14% and 15% for,but it respectively was 15%,13% and 14% during fattening,diets of treatmentⅠand treatment Ⅱwere formulated according to the pattern of ideal protein for growing-fattening pigs.The results showed that the protein level in dietary had no influence on daily wieght gain（DWG） and ratio of feed and weight（RFW） significantly at the different stage（P 〉0.05）.N concentrations of urea in serum of growing-fattening pig from treatmentⅠand treatment Ⅱwere lower than that of control group（P〈0.05）.In room NH3 contents of growing pigs,treatmentⅠand treatment Ⅱ was lower than that of control group （P〈0.05）,but the NH3 content of finishing pig room in treatmentⅠwas lower than that of control group （P〈0.05）.In H2S content of room,there was not significant difference among three groups at the different stage （P〉0.05）.At the stage of growing,compared with the control group,excretion of N pollution in treatment Ⅰand treatment Ⅱ decreased 15.7% and 11.4% ,there were marked difference （P0.05）,but at the stage of fattening,they decreased 15.2% and 8.9%,there was no difference between treatmentⅡ and the control group（P〉0.05）.