Inder to determine the main factors that cause the compression set of rubber materials at elevated temperatures, different test methods of compression set were conducted. The significance of compression set measured by different test methods was analyzed, and a quantitative analysis of the causes of compression set was carried out based on the differences in the results of different test methods. The research results show that rubber materials with strong intermolecular forces due to high polarity are prone to physical compression set, while rubber materials with high bond energy are less prone to chemical compression set. With the increase of test temperature, the physical compression set and chemical compression set of rubber materials both increase, but chemical aging may not necessarily be the main cause of the compression set of rubber materials at elevated temperatures. Quantitative analysis of the reasons for the compression set of rubber materials can provide assistance in the design of rubber formulations and vulcanization processes, as well as in the study of aging kinetics of rubber materials at elevated temperatures.