The invention relates to the technical field of child orthodontic oral cavity supports, and discloses a child orthodontic oral cavity plastic support convenient for adjusting supporting force, the child orthodontic oral cavity plastic support comprises a fixed tooth socket and a side fixing plate, a clamping groove is formed in the outer surface of one end, away from a first convex plate, of the side fixing plate, and a sliding block is slidably connected to the inner surface of the clamping groove; the ends, away from the inner bottom faces of the clamping grooves, of the sliding blocks are fixedly connected with second protruding plates, the ends, away from the sliding blocks, of the second protruding plates are fixedly connected with front fixing plates, the inner side faces of the front fixing plates and the inner side faces of the side fixing plates are fixedly connected with threaded rods, and the outer surfaces of the threaded rods are in threaded connection with moving blocks. The outer surface of the end, close to the side fixing plate or the front fixing plate, of the moving block is fixedly connected with a pressing plate. The wide-mouth end of the pressing plate is driven to extrude the side fixing plate and the front fixing plate by rotating the moving block, so that the side fixing plate and the front fixing plate are continuously close to the inner side surfaces of the teeth, the inner side surfaces of the teeth are more tightly attached to the side fixing plate and the front fixing plate, and the stability is improved.