The utility model discloses a drainage structures is prevented to steel cofferdam, including drainage structures, lay water seepage layer on the bottom sealing by concreting layer of steel cofferdam inboard bottom, lay the bottom water barrier on water seepage layer and lay the lateral part water barrier on the inside wall of steel cofferdam bottom, the steel cofferdam be cube steel sleeve box, the concrete layer of bottom sealing by concreting layer for carry out the shutoff bottom the steel cofferdam, drainage structures includes that four are laid the escape canal on the upper surface of bottom sealing by concreting layer sump pit that bottom sealing by concreting layer upper portion excavation formed and four from top to bottom. The utility model discloses a bottom water barrier is allkept apart cushion cap and back cover concrete layer and steel cofferdam inside wall with the integral water barrier that the lateral part water barrier is formed, can prevent effectively that the interior infiltration of steel cofferdam from getting into the cushion cap to set up the deep water layer between bottom water barrier and back cover concrete layer, all arrange the infiltration in theintegral water barrier outside fast to the escape canal all around in, can effectively solve the drainage problems that prevents of steel cofferdam.