Abstract: The effects of different fermentation temperature (35, 25℃, natural) on the quality of soy sauce had been explored. The results showed that the high-salt diluted soy sauce fermenting under 25℃ exhibited the best quality. The total nitrogen content of 25℃ sample turned to 1.23g/100mL after 60 days' fermentation, and its total acid, reducing sugar content and pH was 2.03g/100mL, 3.37g/100mL and 4.60 respectively. The amino acid nitrogen content of 25℃ sample (0.736g/100mL) was found to be the highest and superior to that of 35℃ and natural samples by 11.68% and 8.55% respectively. Also temperature imposed effects on the free amino acid of soy sauce. 25℃ sample was found to have the highest content. Its essential, umami and sweet amino acids accounted for 43.79%, 29.20% and 22.06% respectively. In addition, Lysine content in soy sauce was determined. It was learned that under 25℃ fermentation Lysine content was 3.91mg/mL and higher than that of 35℃ and natural samples by 16.37% and 15.69% respectively.