Abstract: With the rapid development of power industry in our country, box-type substations and combined transformers are widely used in our power system because of their compactness, high efficiency and reliability. However, their temperature rise has been a key factor affecting their performance and life. In this paper, the temperature rise test system of box-type substation and combined transformer is studied, and its validity and feasibility are verified by practical application. It provides a theoretical support for the optimal design.