The invention provides a rain cover for a disconnector mechanism, and relates to outdoor disconnector rain covers. According to a traditional disconnector, the joint between a rotating connecting rod and a mechanism tank body are not welled sealed, and the direct current of the system is grounded due to raindrop seepage. The rain cover has a flared shape and is provided with an upper opening and lower opening, wherein the upper opening is hooped on the cylindrical surface of the rotating connecting rod of the disconnector and forms sealing at the joint, and the lower opening is located on the tank body of the disconnector mechanism. According to the rain cover, the downward opening flared rain cover is arranged at the joint between the rotating connecting rod of the disconnector and the disconnector mechanism tank body, and direct current grounding of the system can be avoided. The rain cover is used for rainproof protection of outdoor disconnectors in the power industry.