This experiment was conducted to investigate the effect of heating temperature on the protein and amino acid utilization of soybean meal(SBM) in the rumen and small intestine. Soybean meal was treated at the temperatures of 100, 120, 140 and 160℃ in a dry oven and protection ratio of protein was calculated by the NH₃-N concentration changes measured by in vitro incubation at 3, 6 or 12 hrs for each treatment. The ruminal disappearance of heat treated soybean meal(HSBM, 140℃) was measured after of 3, 6, 12 and 24 hrs incubation in situ, and the intestinal utilization was measured by pepsin-HCI digestion method. The followings are the results obtained: In vitro NH₃-N concentration was significantly(P$lt;.01) decreased with increase of heating temperature. The protection ratio of protein was significantly increased with the increase of heating temperature; the increase was 100% in average at 140℃. The dry matter and protein disappearance of nontreated sobean meal (NSBM) and heat treated soybean meal in situ were increased as incubation time increased. Average dry matter and protein disappearance of HSBM were significantly higher than those of SBM The dry matter and nitrogen digestibilities of HSBM(26.22%, 39.17%) by HCI-pepsin digestion were significantly higher than those of NSBM(43.46%, 69%), but NSBM was higher than HSBM in total digestibility. The disappearance of arginine was high in NSBM while that of cystine in rumen was high in HSBM. Proline disappearance was low in both NSBM and HSBM. In average, rumen digestibility of total amino acid of NSBM was higher than that of HSBM, while utilization of essential amino acids was higher in HSBM.