TRIZ theory is based on the basic principle of universal design and application. It builds problem-solving models and proposes solutions to product design problems for certain types of common design problems. It is currently the most effective innovative problem-solving method and computer-aided innovation technology. It has important application value in development and design. The “Fuxing” EMU is one of the main models of China’s long-distance railway transportation. This paper takes the “Fuxing” EMU as the design and research object for conducting in-depth research on the comfort of the “Fuxing” EMU sleeper compartment. Based on the typical behavior of passengers in the sleeper, a complete interactive simulation model is established, and the comfort evaluation is carried out. According to the data analysis results, the accurate problem area is obtained. This paper uses the problem-solving tools in TRIZ theory to analyze and solve the root cause of human-machine problems, and the improvement plan for the key facilities of the product is obtained; overall environment of the train carriage is optimized to form a complete optimization scheme; and the comfort of the scheme is verified by using the simulation software JACK to complete the comfort optimization design systematically of the first-class sleeper compartment of “Fuxing” train. The research enhances the functionality of the interior facilities of the sleeper and improves the ease of use of the facilities, so as to provide a reference for the design of sleeper carriages for EMUs in the future in China.