In order to study the formation mechanism of laser high-speed rotating welded joint of carbon fiber reinforced thermoplastic composites (CFRTP) and titanium alloy, and explore the influence of process parameters on the joint quality, a mathematical model of laser high-speed rotating welding of CFRTP/titanium alloy was established. The temperature distribution was calculated with finite element method, and the influence of laser power, welding speed and spot size on the weld width and penetration was analyzed. The theoretical calculation results were compared with the experimental results. The results showed that the finite element simulation can predict the temperature field distribution of CFRTP/titanium alloy joints. Through the numerical analysis, the weld penetration and weld width of CFRTP/titanium alloy during laser welding can be predicted. The theoretical calculation results are basically consistent with the experimental results, which means that the simulation can provide theoretical support for high quality laser welding of CFRTP/titanium alloy.