Abstract: In order to understand the fatigue characteristics of the carbon fiber yarn and the residual strength of the carbon fiber yarn after fatigue loading, an experiment program was designed and conducted under the static and fatigue loading conditions. The test data was used to establish a micromechanics analysis model for analyzing the fatigue characteristics of carbon fiber composite materials. The stress-life (S-N) curve of the carbon fiber yarn was fitted by the least squares method. A static tension experiment was conducted using carbon fiber yarn after fatigue loading to set up the expression of the residual strength model. The experimental results show that the conditional fatigue limit of the carbon fiber yarn is 80.47% of the static tension strength. Carbon fiber yarn going through a certain number of tension-tension fatigue loading cycles can increase its strength. The residual strength of the carbon fiber yarn increases firstly and then decreases with the increasing of fatigue loading cycles.