The objective of this experiment was to study the correlation between the utilizable crude protein (uCP) and CNCPS components of the seventeen conventional ruminant feedstuffs through chemical analysis methods and short term artificial rumen technique. In this study, one adult cattle fitted with a perpetual large rumen cannula was used as the donor of rumen fluid, rumen fluid was collected and cultivated in vivo. The results showed that there was a positive correlation between the utilizable crude protein and CP, EE, NPN content, however, there was negative correlation between the utilizable crude protein and NDF, ADF, CF. There was significant positive correlation between the utilizable crude protein and PA, PB2, PB3 and PC. But there was significant negative correlation between the utilizable crude protein and CC, CB2 and CA. The regression formula was established as uCP(%)=0.209 PA-0.438 PB1+0.606 PB2+1.664 PB3+2.330 PC-1.219 CC-1.121 CB2+0.275 CB1-1.285 CA+111.862 ( R2 =0.904, n=17, P=0.008<0.01), which had preferable practical value.