The utility model belongs to the technical field of balance cars, and particularly relates to a child balance car with a detachable auxiliary wheel, which comprises a frame, a rear wheel and the auxiliary wheel, one side of the auxiliary wheel is rotatably connected with an L-shaped rod, the surface of the L-shaped rod is provided with a first positioning hole and a first threaded hole, and the outer side of the frame is fixedly connected with a connecting rod. A positioning rod is fixedly connected to the end, away from the rear wheel, of the connecting rod, second positioning holes are formed in the positioning rod at equal intervals, a positioning bolt is movably connected to the interior of the first positioning hole, one end of the positioning bolt penetrates through the L-shaped rod through the first positioning hole, and the positioning rod is located in the L-shaped rod and movably connected with the L-shaped rod; one end of the positioning bolt penetrates through the positioning rod through the second positioning hole. According to the child balance car with the detachable auxiliary wheels, when the auxiliary wheels are replaced, operation can be completed only by rotating the fixing bolts and pulling the handles to drive the positioning bolts to be disconnected with the first positioning holes and the second positioning holes, and the mode is easy to operate.