Abstract: The pyrolysis performance of the unidirectional carbon fiber/epoxy prepreg was studied by thermogravimetric experiment. The morphology of the pyrolysis residue of the unidirectional carbon fiber/epoxy prepreg was analyzed by FESEM, and the material participation involved in the pyrolysis reaction was obtained. The results show that the pyrolysis of unidirectional carbon fiber/epoxy prepreg is divided into three stages in the air. The first and second stages are the pyrolysis of the epoxy resin matrix. The third stage is the pyrolysis of the carbon fiber. The pyrolysis of the unidirectional carbon fiber/epoxy prepreg at different heating rates is that the initial decomposition temperature, the final temperature of the reaction and the maximum mass loss rate are shifted to the high temperature with the increase of the heating rate. The pyrolysis temperature ranges are enlarged gradually, and the mass loss is larger significantly. At the same heating rate, the lumpy unidirectional carbon fiber/epoxy prepreg has a longer pyrolysis time than its powder material, and the pyrolysis temperature is higher at each stage.