The invention provides a PDCdrill bit for rock breaking by thermal spalling. The PDC bit comprises a drill bit body and fixed blades, and PDC teeth, water holes or nozzles are formed in the fixed blades; the PDC drill bit is characterized in that one or more electromagnetic wave generators are arranged on the blades of the drill bit, each electromagnetic wave generator comprises a direct current power supply, an RLC circuit, a high-frequency amplifier and a transmitting antenna, a central water hole is formed in the center of the drill bit, and the drill bit is a steel body bit. In this way, arock is irradiated and heated by electromagnetic waves, and broken by thermal spalling, under the high temperature state, the rock is suddenly cooled when being exposed to water through the central water hole, since the temperature inside the rock changes rapidly, a temperature gradient is formed inside the rock, and the thermal fracture or thermal impact phenomenon occurs in the rock and causesdeterioration of various mechanical properties of the rock; and the drill bit uses two modes of thermal spalling and scraping and cutting of the PDC teeth to break the rock in a coupled mode, thus therock breaking efficiency of the drill bit is improved, the difficulty of the PDC teeth entering the formation can be lowered, the service life of the PDC teeth is prolonged, and comprehensive performance of the drill bit is improved.