The invention discloses a diamond drill bit and belongs to the technical equipment field of petroleum and natural gas drilling engineering, mine engineering, building foundation engineering construction, geologic drilling, tunnel engineering, hydrology, non-excavation and the like. The diamond drill bit comprises a drill bit body and a plurality of blades extending from the drill bit body, wherein cutting elements are arranged on the blades, at least one annular blank belt surrounding the center of the drill bit body is arranged on the drill bit body, and the blades in the position of the annular blank belt are inwards concaved to form circumferentially through grooves. The cutting energy consumption of the drill bit can be reduced, the rock breaking efficiency can be improved, meanwhile, transverse vibration of the drill bit can be inhibited, impact failure of cutting teeth of the drill bit is effectively reduced, the anti-drift capability of the drill bit in directional drilling is enhanced, large-size rock chips can be produced, the geological logging quality is improved, and the underground stratum information analysis and judgement accuracy under the condition of real drilling is improved.