The invention discloses a high-temperature waste heat recovery system for a diesel engine. The technical scheme is that an air compressor, a regenerator, a thermo-electric generator, an EGR heat exchanger and an expander are sequentially connected to form a Brayton air regenerative cycle system, and an airflow regulating valve is connected with the air inlet of the air compressor; high-temperature exhaust gas discharged by an engine is output in two ways: one part sequentially passes through a turbine and the thermo-electric generator and then is discharged to the atmosphere, the other part is mixed with supercharged air from a supercharger through the EGR heat exchanger, and the mixture enters the air inlet of the engine; and Brayton circulating air serves as the cold end of the thermo-electric generator, exhaust passing through the turbine serves as the hot end, and the thermo-electric generator pre-heats the Brayton circulating air while outputting power. The high-temperature waste heat recovery system can efficiently utilizes high-temperature waste heat of an internal combustion engine, thereby improving the fuel economy of the internal combustion engine and lowering the heat load of the system. Meanwhile, the system has a relatively simple composition, ensures safe and environment-friendly running, is convenient and flexible in layout, and can be easily implemented in the internal combustion engine.