The present invention discloses a waterproof structure of a pad, a waterproof pad, and a method for forming the waterproof structure. The waterproof structure includes a first dielectric layer, having an annular hollowed-out recess along the periphery of the first dielectric layer and a metal annular zone formed in the annular hollowed-out recess, and a second dielectric layer, formed above the first dielectric layer and located under the pad and having multiple first through-holes along the periphery of the second dielectric layer and multiple metal posts formed in the multiple first through-holes, where the multiple first through-holes form a hollow annular through-hole chain and the metal annular zone maintains an electrical connection with the multiple metal posts.