As a primary means of diagnosing long-term latent faults in transformers, dissolved gas analysis (DGA) can effectively guide transformer fault diagnosis and condition assessment through the analysis of dissolved gas content and proportions in oil. To investigate the gas generation patterns of transformers with local overheating and partial discharge faults under different temperatures, a test platform for simulating gas generation patterns in oil-paper insulation with controllable oil temperature was established. Oil samples were collected at different time points during the fault development process for DGA, providing information on the characteristic gas generation in the oil-paper insulation system under varying oil temperatures. The results indicate that oil temperature has a significant impact on the generation and dissolution of characteristic gases during surface discharge in oil-paper insulation. Methane remains the most active hydrocarbon gas, while carbon dioxide and hydrogen are the primary products. Carbon monoxide and ethylene concentrations exhibit relatively stable changes. Acetylene concentration fluctuates significantly with temperature. Increasing oil temperature may lead to a decrease in the concentration of certain gases.