A steel body density detection apparatus comprises an apparatus body, an upper cover, an electronic scale, a water inlet and a water outlet, the top of the apparatus body is provided with the upper cover, the left sidewall of the apparatus body is provided with an opening, the opening is provided with a conveyor belt A, the electronic scale is arranged below the conveyor belt A and is positioned in the apparatus body, the sidewall of the electronic scale is provided with an LED display screen, the top of the electronic scale is provided with a buffer pad, the electronic scale is connected with a control device through a lead, the bottom of the electronic scale is provided with a supporting plate, the supporting plate is connected with a supporting frame through a connecting block, the supporting frame is positioned on the right sidewall in the apparatus body, a water level collector is arranged below the supporting frame, and a calibrated scale is arranged below the water level collector. The detection of the density avoids the use of steel body with bubbles generated in the pouring process, so the life and property loss can be effectively prevented.