Objective To screen the raw pepper varieties suitable for semi-finished chili sauce in red sour soup.Methods Ten different varieties of high-quality peppers from Guizhou Province are taken as research objects. The aspects below are studied among different varieties of mature fresh peppers during fermentation: the changes of color, total acid, nitrite, amino acid nitrogen, soluble solids, and other quality indicators, as well as the content of capsaicin and organic acids at the end of fermentation. Then, sensory evaluation is conducted on the semi-finished chili sauces.Results The results show that Guizhou Erjingtiao pepper, sheep-horn pepper, Honghang pepper, and screw pepper produce lower nitrite, higher acid, amino acid nitrogen, and organic acid during fermentation, while maintaining ideal color and excellent overall quality. Millet spicy and hot girl can maintain bright and vivid color during fermentation, but they are relatively weak in the acid production capacity, nitrite content, and other indicators, with high capsaicin content. Due to insufficient flavor coordination, their sensory acceptance is low. The capsaicin content in the semi-finished chili sauce prepared with cayenne pepper is the lowest, only 1.12 μg/g, but the acid production capacity is weak and the nitrite content is high, reaching a peak of 16.49 mg/kg. Beauty peppers and strawberry red peppers are brightly colored and moderately spicy, but they are high in nitrites. Through the principal component analysis of the semi-finished fermented chili sauce, a correlation is found between the fermentation quality indexes in the semi-finished chili sauces. Then, a comprehensive evaluation model is constructed for the effect of raw pepper varieties on the fermentation quality of semi-finished chili sauce in red sour soup. The model is Y=0.525Y₁+0.286Y₂+0.113Y₃.Conclusion Semi-finished chili sauces made of Honghang pepper, Guizhou Erjingtiao pepper, sheep-horn pepper, and screw pepper are bright and red, with a typical lactic acid fermentation aroma and a high comprehensive quality score, suitable for raw materials to ferment semi-finished chili sauce in red sour soup.