Because of the influence of high ash fine mud in the flotation feed in Xingtai Coal Washing Plant, the flotation effect is not ideal all the time. According to its own production conditions and equipment layout characteristics of the  plant, the series flotation of the flotation machine and the flotation column was realized in the single opening B system through the modification of the pipeline, and the results of two industrial tests were better, thereby laying the foundation for further realization of the series flotation transformation.