Asphalt deposits seriously affect the development of oilfields. In order to clarify the influence of colloid on asphaltene deposition in the process of CO2 flooding，taking simulated crude oil with different colloid and asphaltene mass concentration ratio as the research object，the microscopic visual experiments were carried out to simulate the asphaltene deposition and to analyze the change of composition，physical properties，and solid particles size，and the effect of the colloid concentration on the stability of asphaltene was explored. It is indicated that the asphaltene was wrapped in colloid with a spherical shape，which could keep asphaltene stable. When the mass ratio of colloid to asphaltene rose from 1∶1 to 6∶1，the asphaltene deposition and sedimention potential of the simulated crude oil increased first and then decreased，while the viscosity of the simulated crude oil decreased first and then increased. The viscosity was the lowest，and asphaltene deposition and sedimention potential were the largest when the mass ratio of colloidal to asphaltene was 2∶1. The asphaltene deposition was directly related to the colloid content. It was verified that there was a pair of forces between the colloid and the asphaltene—adsorption force and dispersing power. The amount of asphaltene precipitation was related to the effect of this pair of forces in the process of CO2 flooding.