In this study, the effect of fuel droplet size and injection temperature on the operating performance of a kerosene-oxygen pulse detonation rocket engine was experimentally investigated. A special particle size analyzing system was utilized to measure the kerosene droplet size. In addition, another experimental test system was also established to investigate the operating performance of a kerosene-oxygen pulse detonation rocket engine at the frequency of 10 Hz. Three sizes of pressure-swirl nozzles were used to the experiment. The experimental results indicated that the SMD of kerosene droplets gradually decreased as the injection temperature increased, and three temperature ranges are separately discussed. The experiment results demonstrated that higher injection temperature and smaller SMD were beneficial to improve the operating performance. The thrust and specific impulse were very sensitive to the SMD value. As the injection temperature of the PDRE increased from 293 to 493K, the thrust increased by 23.42,14.38, and 19.53%, and the specific impulse increased by 21.62, 19.61, and 15.89%, for nozzles 1, 2, and 3, respectively.