The invention relates to a floor building waterproof structure and a water drip forming formwork. The floor building waterproof structure comprises a building main body formed by pouring of concrete.A first waterproof boss is arranged on the bottom face of the building main body and located in the junction position of the bottom and the outer wall face of the building main body. The face, adjacent to the first waterproof boss, of the bottom face of the building main body is flat. The width d1 of the adjacent face is at least 80 mm. According to the floor building waterproof structure, in theprocess that the water drip forming formwork is detached after the building main body is subjected to pouring forming, the lateral force of internal and external corners of a water drip is small, andaccordingly the undesirable phenomenon of collapse of the internal and external corners of the water drip can be reduced. In addition, outer wall face construction of painting putty, coating and the like on the bottom face of the building main body is facilitated, and the outer wall face construction effect is good.