The effect of refined cotton, carbon fiber content and length on the safety of caseless ammunition and self-ignition temperature of simulating bore test was analyzed by testing the ignition point of 5 s delay of the propellants containing carbon fiber or refined cotton,impact sensitivity and temperature of simulating bore test. Results show that the impact sensitivity of the caseless ammunition is depressed when adding carbon fiber with content of 0.5%-1.5% and length of 10 mm, the anti-spontaneous-combustion temperature is hoisted by adding carbon fiber and the anti-spontaneous-combustion time is prolonged at the same temperature.