The invention belongs to the technical field of paint mist flocculant production, and particularly relates to a paint mist flocculant, a preparation method and application thereof. The existing paint mist flocculating agent has poor flocculation effect, COD removal, corrosion prevention and rust prevention effects, so the invention provides the paint mist flocculating agent, which comprises the following raw materials of A agent and B agent; the A agent comprises, by weight, 1-5 parts of an amino compound, 1-5 parts of an aldehyde compound, 30-60 parts of bentonite and 10-20 parts of polyaluminium chloride; the agent B comprises 0.5-1.5 parts of polyacrylamide, 0.3-1 part of bactericide, 20-40 parts of antirust additive and 2-6 parts of defoamer; the agent A and the agent B both comprise 300 parts of water. The invention also provides a preparation method and application of the paint mist flocculating agent. The flocculant is used for the paint mist removal rate in the wastewater, which is more than 95%, can reduce SS solid suspended matters, simultaneously reduce COD by more than 55%, and can be widely used for treating paint in the wastewater.