Abstract: In view of the fact that conventional mud acid acidizing effect is not satisfactory for wells with low temperature, low pressure, low watercut and high viscosity in shallow blocks of Weicheng Oilfield, this paper presents this alkali-acid composite plug removal technology, which integrates the advantages of ASP flooding and CO2 flooding, and uses the previa flooding system and post acid system. The previa flooding system is mainly composed of guar, crosslinking agent, sodium alkyl benzene sulfonate, Na2CO3 and NaHCO3, which adopts the principle of ASP flooding, stripping and displacing the crude oil attached to the surface of rocks pore to avoid residues. The post acid system is conventional mud acid liquid, the function of which is to remove dirt, enlarge pores and also react with the previa flooding system to give off heat and CO2 to reduce viscosity and enhance emission. Its plug removal effect was studied by micro-model and physical model. The experiment and field application showed that, in the alkali-acid composite plug removal technology, the previa flooding system created favorable conditions for post acid system to remove formation pollution; the reaction between alkali and acid produced large amount of CO2 and heat, which combined with acid and effectively solved the problem of organic pollution and inorganic pollution in wells of low temperature, low pressure and low watercut.