Abstract: The wet electrostatic precipitator (WESP) has a much higher capture rate for fine particulate matter PM_2.5 than the traditional dry electrostatic precipitator. In order to achieve zero emission of smoke and dust, it is proposed to add chemical coagulant into wet electrostatic precipitator. The influences of the medicine type, concentration and addition point of chemical coagulant on coal dust coagulation effect and collection efficiency are studied. The results show that the addition of chemical coagulant can promote the coagulation of coal-fired dust particles. After the addition of pectin (PG), the median diameter of dust particles increases from 28.19μm to 45.28μm. At the concentration of PG is 1.0×10⁻²g/L, the coagulation effect is the best, and the collection efficiency reaches 96.42%. Polyacrylamide (PAM) has the best corona discharge performance. The synergistic effect of PAM and water vapor can improve the coagulation effect, 1.0×10⁻²g/L PAM and 3.2kg/h water vapor synergize, and the collection efficiency reaches 96.68%. The addition of chemical coagulant promotes the coagulation of fine dust particles and enhances the capture effect of WESP for fine particles.