The invention relates to an external maintenance-free seal cover of a main shaft for a drive part of an isolating switch in a transformer substation, and in particular to a novel external maintenance-free seal cover of a main shaft for a drive part of a 66KVGW5-60 type isolating switch (namely a disconnecting link) in a transformer substation, belonging to the technical field of electric power. The external maintenance-free seal cover comprises a bolt and a seal cover, wherein the bolt penetrates through an opening on the top of the seal cover to be connected with the seal cover; specifically, the bottom of the seal cover is provided with a groove, and the groove is internally provided with a seal glue cushion; and the bottom of the bolt is provided with a groove, and the groove is internally provided with a seal glue ring. The external maintenance-free seal cover provided by the invention is additionally provided with the seal glue cushion and the seal glue ring, and a needle bearing part under the seal glue cushion is coated with a lubricating grease coating layer which plays a role in lubrication, air isolation, and acid and alkaline substance corrosion resistance, so that the seal cover is unlikely to be corroded by rainwater, the functions of water resistance, dust resistance, moisture resistance, corrosion resistance and acid and alkaline substance corrosion resistance are achieved, and sealing/unsealing accidents caused by the corrosion of the main shaft of a drive mechanism of the 66KV isolating switch (namely the disconnecting link) can be thoroughly solved. Therefore, the external maintenance-free seal cover is suitable for wide power industries.