Thermal performance evaluation test is a formal test work that must be carried out by enterprises of electronic products, it is also a key quality control link of products. This paper presents a test design method for evaluating the thermal performance of electronic products based on the worst conditions, and its basic idea, specific design contents and process steps are discussed in detail. Selects a inverter air conditioner outdoor unit’s electronic control component as the object to apply this method to design the worst test conditions which can be used to evaluate the application object’s thermal performance, the engineering application shows that the efficiency and effectiveness of the application object’s thermal performance evaluation test have been effectively improved. The thermal performance evaluation test design method proposed in this paper, which has a good engineering application prospect, provides a reference for the electronics industry.