The invention discloses a bi-directional powder feeding device for 3D printing, including a fixing plate. The bottom of the fixing plate is provided with an electric sliding rail, electric sliding blocks are arranged on the both side of the inside of the electric sliding rail, powder spraying heads are arranged at the bottoms of the electric sliding blocks, a box body is arranged at the middle position of the top of the fixing plate, a hopper is arranged at the top end of the inside of the box body, a heater is arranged on one side of the box body, and a control panel is arranged on the otherside of the box body. According to the invention, a bi-directional powder feeding mechanism composed of a swirl fan, a powder feeding bin, a three-way pipe, a conveying pipe and the powder spraying heads is installed, through the use of the bi-directional powder feeding mechanism, powder can be simultaneously discharged from both sides of the device, the powder feeding speed of the device is improved, the 3D printing speed is accelerated, the heater is arranged on one side of the box body, and the inside of the box body can be heated through the heater, so as to ensure the drying of a powder material, the blockage of the powder material is prevented, and the continuous use of the device is facilitated.