Cutting-carrying mechanism of CO2 is basic for rational hydralics design, which helps to achieve safe and efficient use of drilling with supercritical carbon dioxide. In this view, change law of partical size distribution and influences of drilling parameters on cutting-carrying efficiency is simulated and analyzed, with consideration of the influences of physical parameters change of CO2. Results show that there is no positive correlation between change law of partical size distribution and partical diameter for the existence of mutual interference, which demonstrates Oulerian method used to analyze cutting-carrying mechanism feasible. Pressure and temperature influences the change law of partical size distribution, and the cutting-carrying efficiency increases as the increase of pressure and the decrease of temperature, which agrees with experimental results. Larger displacement and lower ROP helps to improve cutting-carrying efficiency, and actual critical displacement is larger than theoretical value calculated with Ahemd method. The cutting-carrying efficiency decreases as eccentricity increases and then increases as the eccentricity is beyond 0.8. Outcomes offers important basis for the improvement of practical skills.