Investigating the gas production characteristics of insulation oil thermal cracking at the atomic level is of great significance for transformer fault diagnosis and condition assessment based on dissolved gas analysis. This paper simulates the thermal cracking kinetics of multi-component mixed oil using molecular dynamics, analyzing the gas production characteristics of modified natural esters and multi-component mixed oil at different temperatures. The results show that during the thermal cracking of multi-component mixed oil, C2H4 is generated in large quantities at various temperatures and is the most abundant characteristic gas. The content of H2, CO, CH4, C2H2, and C2H6 gradually increase with rising temperature, while CO2 is the first gas to be produced and tends to saturate. The contents of H2, CH4, C2H2, and C2H4 show significant trends with temperature changes and can be used as key characteristic gases for diagnosing faults and conditions of multi-component mixed oil transformers. This finding provides guidance for developing maintenance strategies for transformers using multi-component mixed oil.