As precursors of aromatic compound, Tyrosine and Phenylalanine have great influences on the taste and quality of Baijiu(Chinese liquor). To detect source of Tyrosine and Phenylalanine during the liquor-making process, the free amino acid content in raw materials and fermented grains from different fermented stages were detected by high-performance liquid chromatography (HPLC), and contributions of different brewing microorganisms and five raw materials to the contents of tyrosine and phenylalanine were investigated by solid-state fermentation. Results showed that tyrosine and phenylalanine were mainly produced in the saccharification process and the early stages of fermentation. Bacillus subtilis JQ11 was one of the major microorganisms that hydrolyzed grain proteins to amino acids. The contributions of different raw materials to amino acid composition were different. Among them, glutinous rice tended to be hydrolyzed to generate relatively higher contents of tyrosine and phenylalanine, presumably had a greater contribution to aromatic compounds.