Qiangnai interface agent is a water-based polymer interface agent used for basic level processing in the cement-based and gypsum-based self-leveling construction. Featuring excellent film-forming properties, it closes the capillary pores of the basic level and greatly reduces the water absorption rate of the porous basic level, thus making for self-leveling construction. Moreover, it strengthens the adhesion between the base level and the self-leveling level, and plays the role of a bonding bridge to effectively prevent hollowing, cracking, and blistering.