The invention discloses a waterproof transmission chain device. The waterproof transmission chain device comprises a first gear and a second gear; the outer sides of the first gear and the second gearare in transmission connection with a transmission chain; the transmission chain comprises first chain plates and second chain plates; the first chain plates and the second chain plates are alternately arranged; a first groove hole is formed in one side of the top of each first chain plate and the corresponding second chain plate; a threaded rod is connected to the inner side of the first grooveholes; the two ends of the threaded rod are located on the outer sides of the first chain plates and the second chain plates and are each in threaded connection with a nut; one side of the first gearis fixedly connected with a first motor; and the outer side of the output end of the first motor is sleeved with a first rotating plate. The invention relates to the technical field of transmission mechanical devices. According to the waterproof transmission chain device, water spots on the chain can be effectively cleared, meanwhile, clearing can go deep into the transmission chain, water drops on the transmission chain can be guided onto water-absorbing sponge, the water drops on the transmission chain are reduced, and meanwhile it can be prevented that water drops dropping from the upper portion drop onto the transmission chain.