The invention provides a top rainproof device of an outdoor disconnecting link auxiliary contact box. The top rainproof device has a round cap-shaped structure; a center hole is formed in the top rainproof device; a bonding surface is formed on the inner circumference surface of the center hole; the top rainproof device is bonded on the outer circumference surface of a transmission rod by the bonding surface; the top rainproof device covers a bearing of the transmission rod entering the outdoor disconnecting link auxiliary contact box and is used for preventing rainwater from entering the outdoor disconnecting link auxiliary contact box through the bearing between the transmission rod and the outdoor disconnecting link auxiliary contact box. The bonding surface of the top rainproof device is closely bonded with the outer circumference surface of the transmission rod, and the top rainproof device completely covers the bearing of the transmission rod entering the outdoor disconnecting link auxiliary contact box, so that the rainwater is prevented from entering the outdoor disconnecting link auxiliary contact box, and a good rainproof function is realized.