The share of water-based paint in the paint market is rising rapidly year by year, but there are some problems such as the low removal rate of water-based paint and secondary pollution in the treatment of water-based paint wastewater by traditional paint mist condensate. In this paper, a two-dimensional exfoliated montmorillonite paint mist condensate was developed, which significantly improved dispersion stability and removal rate of water-based paint in water-based paint wastewater of montmorillonite paint mist condensate. Atomic force microscope (AFM), scanning electron microscope-X-ray energy spectrum (SEM-EDS) analysis, Zeta potential analyzer, Fourier transform infrared spectrometer (FTIR) and ultraviolet spectrophotometer were used to explore the influence of two-dimensional exfoliation on the montmorillonite paint mist condensate and its mechanism. The results show that the mechanism of treating water-based paint wastewater by montmorillonite paint mist condensate is mainly that hydrogen bonds are formed between hydroxyl groups in montmorillonite, O in Si—O and carboxyl groups of water-based paint, so that water-based paint is adsorbed on the surface of montmorillonite. Montmorillonite with higher peeling degree has stronger electronegativity and can maintain better dispersion stability. With the increase of peeling degree, the dispersion stability and removal rate of water-based paint of montmorillonite paint mist condensate are significantly improved. When the dosage of two-dimensional exfoliated montmorillonite is 1.125% (volume fraction) of water-based paint wastewater and the dosage of cationic polyacrylamide is 1.000% (volume fraction) of water-based paint wastewater, the removal rate of water-based paint reaches 98.770%. Compared with the commercially available montmorillonite paint mist condensate, this product has higher removal rate of water-based paint after treating water-based paint wastewater.