Aiming at the problem of corona occurrence of power transmission and transformation fittings in high humidity areas, the influence of humidity on the corona characteristics of the rod-plate electrode is studied by simulating the electric field of the rod-plate electrode and the corona of the rod-plate electrode under different humidity law. The results show that when there are particles in the gap between the rod and the plate, the electric field distribution will be significantly distorted. When the humidity is high, depending on whether the connection direction of the particles is the same as the ray direction of the tip of the rod electrode, the presence of particles has a different effect on the electric field. When in the same direction, the presence of particles will promote the development of the flow column; when it is perpendicular, the presence of particles will hinder the development of the flow column; In the range of relative humidity of 30%~60%, the corona initiation voltage decreases with the increase of relative humidity. In the range of relative humidity of 60% to 85%, the voltage increases with the relative humidity, but the amplitde is smaller. For different electrodes, the relationship between corona initiation voltage and relative humidity shows the same trend.