Abstract: In this stuy,in order to explore the special volatile compounds of Qula casein as well as their source,the SPME- GC- MS had been used to detect the volatile chemistries of caseins extracte from different raw materials as well as Qula and fresh milk. The results indicated that acetic acid,3- oxhydryl- 2- butanone,nonanal,toluene and sulfur dioxide were the distinctively substance of the Qula casein,which had unique contribution to the Qula casein special odor and acetic acid was root in Qula.3- oxhydryl-2- butanone was partly root in Qula,and partly from the production process.Nonanal,toluene and sulfur dioxide were from the preparation procedure. In addition,regional divergence of Qula had a biggish contribution to the smell of casein but not the color of the raw material.