The action mechanism of paint mist flocculant was described.The influence of the application proportion of paint mist flocculant on the slag state of circulating water in the field of oil-water mixing was analyzed in detail.The common problems and adjustment methods in the field application of paint mist flocculant were summarized.The successful application cases of paint fog flocculant in auto parts industry and construction machinery industry and the on-site detection parameters were presented.