Industrial syngas contains a large amount of CO₂， and the utilization of CO₂ resources is of great significance to the current improvement of environment. The homoacetogenesis in the process of anaerobic fermentation has characteristics of autotrophy and heterotrophy. It can use CO₂ and H₂ to produce acetic acid， and degrade glucose to produce volatile fatty acids （VFAs）. The autotrophic characteristics of homoacetogenic bacteria were used to study its ability to convert CO₂ into resources and the effects of headspace H₂/CO₂ ratio， the type of carbon sources and pH on the synthesis of homoacetogenic reaction products. The results showed that high pH was beneficial for homoacetogenic bacteria to utilize H₂/CO₂ mixed gas for autotrophic reactions. When pH=5 and H₂/CO₂=3∶1， the yield of VFAs including acetic acid， propionic acid and butyric acid was the highest， reaching 3 369.89 mg/L， and the proportion of acetic acid was 76.1%. When glucose and H₂/CO₂ mixed gas were used as a common carbon source， the homoacetogenic bacteria preferentially used glucose for heterotrophic reaction， and then the H₂/CO₂ mixed gas began to be utilized. The results of correlation analysis showed that there was a weak positive correlation between the content of VFAs and the value of pH， but a negative correlation with H₂/CO₂， indicating that the content of CO₂ has a greater impact on the autotrophic pathway of homoacetogens. A prediction model with BP neural network for homoacetogenic reaction was established， which accurately predicted the yield of VFAs synthesized by homoacetogenic bacteria with H₂/CO₂ mixed gas as the carbon source（R²=0.966）.