The invention relates to a composite 
cutting diamond drill bit. The 
drill bit comprises a 
drill bit body, fixing blades, disc cutters, 
water channel grooves and water passages or spray nozzles. The fixing blades extend from the 
drill bit body and are fixedly connected with the 
drill bit body, the 
water channel grooves are located among the fixing blades, blade 
cutting elements are arranged on thefixing blades, and one or more 
disc cutter cutting units are arranged on the 
drill bit body, wherein each 
disc cutter cutting unit is composed of a 
disc cutter, disc cutter cutting teeth on the disc cutter and a disc cutter shaft; the disc cutters are installed on the disc cutter shafts or are integrated with the disc cutter shafts, and the deviation 
angle alpha of the disc cutters is larger thanor equal to 20 degrees and smaller than or equal to 90 degrees. The composite cutting 
diamond drill bit is characterized in that one or more disc cutters are arranged on one fixing blade or in the 
water channel groove between every two fixing blades, the two sides of each disc cutter cutting unit are supported on supporting bodies respectively and rotatably connected with the supporting bodies, the service life of disc cutter bearings can be effectively prolonged, the safety performance of the disc cutter cutting units during use is improved, the 
rock breaking efficiency of the drill bit is effectively improved, and the service life of the drill bit is effectively prolonged.