In order to study the influence of clay mineral content on the oil displacement efficiency of ternary composite flooding in three types of reservoirs in Daqing，using natural cores with similar porosity and permeability but different content of clay，oil displacement experiment was developed. The core before and after the experiment was analyzed by X-ray diffraction and nuclear magnetic resonance. The emulsified particle size of the produced fluid was also tested. The results showed that with the increase of clay mineral content，the range of oil recovery improved by alkali-surfactant-polymer（ASP）flooding increased first and then decreased. When the clay mineral content was 9.5%，the recovery of ASP flooding had the largest growth rate（15.7%）. There was obvious emulsification in the produced solution. When the clay mineral content increased from 2.3% to 9.6%，the emulsion changed from water-in-oil type to oil-in-water type. The particle size kept decreasing. The higher the clay mineral content，the easier migration of kaolinite in mineral was. It made the pore throat of the core larger. A specific seepage channel formed，leading to the poor water flooding effect and the reduction of ultimate recovery factor. The content of clay mineral had a great influence on the oil displacement efficiency of ASP flooding in Daqing oilfield. The oil recovery degree of water flooding and ASP flooding was affected mainly through changing the type of emulsion in produced liquid，particle size and the size of core pore throat after mineral migration. As a result，the final recovery factor was changed.