Abstract: Kitchen waste can produced ethanol by directional fermentation, but the complex pretreatment leaded to long treatment time and increased process complexity. In this study, through the comparative test of direct inoculation of yeast and inoculation of yeast after sterilization, the degradation and production law of ethanol, ethanol precursor reducing sugar and reducing sugar precursor starch in the fermentation system were analyzed, and the feasibility and law of ethanol production by direct inoculation of kitchen waste with yeast in solid-state anaerobic fermentation were discussed. The results showed that the addition of yeast could promote the solid anaerobic fermentation of kitchen waste to produce ethanol. The ethanol concentration after inoculation with yeast could reach 11.86~12.09 g/L, which was 8.41~8.57 times higher than that of the blank group, and was higher than that of 6.88-10.02 g/L after sterilization pretreatment; The analysis based on Gompertz model also confirmed the results. After inoculation with yeast, the system ethanol production potential (P_m) and unit maximum ethanol yield (R_m) also increased, but the inoculation amount did not have a great impact on the P_m and R_m of kitchen waste. The analysis results of reducing sugar of ethanol precursor showed that inoculating yeast could play a role in the early stage of fermentation, which promoted the rapid decline of reducing sugar in the system to 43.37-46.55 mg/g in 0-4 h, thus accelerating the stabilization process of kitchen waste. However, within 4-24 h, due to the inhibition of secondary metabolites, reducing sugar in the system did not appear obvious production and degradation. At the same time, the analysis results of starch hydrolysis of reducing sugar precursor show that inoculating yeast can increase the hydrolysis rate of starch from 19.36% to 27.90-37.57%, but the hydrolysis will no longer occur when the starch content is 274.02-316.51mg/g. Therefore, improving the efficiency of reducing sugar produced by starch hydrolysis has become an urgent problem to be solved.