In order to adjust the cohesive force between dust particles and collecting plates of electrostatic precipitator,the effect of coat on collecting plates to force conditions of dust particles is analyzed,the theoretic explanation on the characteristics of coat on collecting plates is made.Some appropriate coating materials were selected through calculation,and a lot of experiments on the effect of coat on cohesive force of dust were carried out,so that the reasonable resistivity range of coat was determined,at the same time,it was proved that suitable coat on collecting plates can effectively adjust the cohesive force between dust and collecting plates.