The high-frequent pulsing ablation of C/C-SiC-ZrB₂-ZrC composites under millisecond-scaled single loading for different cycles was studied. The sample was ablated and cooled by plasma and airflow alternately on a self-developed bench. Results indicated that the ablation rates decreased quickly before 1000 cycles and then declined gradually until impact for 2000 cycles. Microstructure, phase and surface temperature analyses suggested that an incomplete layer of mixed ceramic ablation product was formed on the surfaces of the tested composites and the amount of the bare carbon tended to be steady after 1000 cycles. The ablation product layer weakened the thermal stress-induced mechanical erosion and protected the carbon from erosion, which led to the evolution of ablation rates.