To address the demand for efficient pulp conditioning technology in coal slime flotation, this paper designs a combined pulp conditioning device based on jet mixing, pipeline mixing, and drop plate mixing. Through a combination of COMSOL numerical simulation and physical experiments, parameter optimization tests were conducted for each stage of jet, pipeline, and drop plate. The pulp conditioning effect was verified through flotation tests. The results indicate that when the ratio of the incident flow rate to the instantaneous mixing volume in the tank is 0.414, an optimal flow field is achieved in the tank for the mixing of reagents and pulp. Increasing the number of mixing units within the pipeline mixing enhances the turbulence intensity of the fluid, thereby further improving the contact probability between reagents and mineral particles. When the angle of the drop plate is set at 15°, particles are more evenly distributed on the baffle plate, which can increase the pretreatment time and enhance the effect of the baffle bars. Compared with the slurry flotation of 1.5 L single tank flotation machine, the flotation test was carried out on the slurry after the slurry was adjusted by the Jet - Pipeline - Drop plate combined slurry adjustment device. The yield of clean coal was increased by 6.85 %, and the recovery rate of clean coal combustible was increased by 8.85 %.