Composite tubes offer significant weight reduction advantages over steel tubes, but their heat dissipation performance is inferior. To research the heat transfer characteristics and influencing factors of a small caliber composite tube, a one-dimensional unsteady-state heat transfer model was developed using the finite volume method, and its accuracy was proved by experimental data. This model was utilized to numerically simulate the heat transfer process of a small caliber composite tube, revealing the radial distribution and variation of temperature within the tube. The study results indicate that the heat dissipation performance of the small caliber composite tube is inferior to the steel tube in same size, failing to meet the specification of continuous heating of 120 cycles. Under the heating specification of 30 cycles, the highest temperatures were 478.8 °C at the inner surface of the liner, 223.8 °C within the composite jacket, and 227.1 °C at the outer surface of the composite tube. The composite jacket exhibiting a lag in temperature change compared to the steel liner. These findings provide guidance for the design of composite tubes.