It is of great significance to study the electric field and force of metal particles on the dielectrically coated electrodes of gas insulation line (GIL) to investigate the reasons of coating enhancing the lifting field strength of particles. Calculation models of the electric field distribution of particles on electrodes with or without dielectric coating are established respectively. Electric field calculation results show that the maximum value of the electric field under bare electrode appears at the top of the particle and is subjected to an upward electric field. While the maximum value of the electric field under dielectrically coated electrode appears between the particle and the coating, and the direction of the electric field force is related to the electric charge, and there are two kinds of situations, downward or upward. The partial discharge between the particles and the coating is the main mechanism of particle charging under the dielectrically coated electrode, when the electric field strength reaches the lifting field strength under bare electrode, the particle may still be uncharged, but it is subjected to the downward electric field force. Therefore, the decrease of electric charge and the downward of the electric field force are the reasons enabling coating to enhance the particle lifting field strength.