Abstract: To improve the load capacity of the oil powered quadrotor unmanned aerial vehicle, carbon fiber reinforced polymer composite (CFRP)-metal transmission shafts are studied. The factors affecting the torsional strength of CFRP-metal transmission shafts are the quality of CFRP pipe holes and the extrusion effect of pins on connecting holes during transmission. By studing the mechanical behaviors causing delamination damage at the entrance and exit of CFRP tube, the influence mechanism of the quality of CFRP pipe holes was revealed and the hole making process was optimized. A comparative analysis between pin-connection CFRP-metal transmissions shafts and hybrid CFRP-metal transmission shafts with inner and outer bushing was carried out by torsion tests. The results show that the addition of the inside and outside aluminum alloy bushing of CFRP tubes can effectively reduce the delamination damage during drilling. The quality of the entrance and exit of holes can be increased by 4.4% and 8.3%, respectively. Meanwhile, the extrusion effect of the pins on the connecting holes is restrained. The torque values of the optimized transmission bearing is increased from 499 N·m to 952 N·m.