The utility model provides a CT secondary terminal box waterproof device, which is characterized by comprising a base arranged under an outdoor terminal box, wherein the bottom part of the outdoor terminal box is provided with spillway holes, a water collecting base plate is arranged under the outdoor terminal box, a drain pipe communicated with the water collecting base plate is arranged at the lower part of the water collecting base plate, the bottom part of the drain pipe is closed, the drain pipe is provided with a drain hole in the side wall close to the bottom part, a steel bead used for blocking the drain pipe is arranged in the drain pipe, and a spring is arranged under the steel bead. The CT secondary terminal box waterproof device is simple in structure, achieves the effects of automatic drainage e in case of water seepage or moisture condensation and sealed air inflow in anhydrous state by utilizing the design of adopting the spring and the steel bead at the lower half part in the drain pipe and reasonably arranging two drain small holes, prevents tiny animals from entering into the box body, and achieves the comprehensive functions of waterproof, moisture-proof and animal prevention.