In order to study the effect of temperature，oil displacement agent，wettability and their interactions on heavy oil thermo-chemical recovery，response surface methodology was used to design experimental schemes and analyze their results. The nature and the degree of the influencing factors and their interactions were studied in lab experiments. Contribution of various factors and their interactions on heavy oil thermo-chemical recovery were made clear by use of self-defined weight of influencing factors. The results show that the weight of temperature on heavy oil thermo-chemical recovery is 58%，the weight of chemical agent is 23.3%，and the weight of their interaction is 11.4%. Therefore，temperature，chemical agent and their interaction are the dominant mechanism of thermo-chemical recovery of heavy oil. Quantitative study on effect of various influencing factors and their interactions on recovery during thermo-chemical flooding makes synergistic effects of thermal and chemical agent clear. The study deepens the understanding on heavy oil thermal-chemical flooding mechanism.