An auxiliary wheel structure for kid bicycle includes a mounting bracket fixedly mounted to an end of a rear wheel hub of the bicycle, a lifting arm pivotally connected at an end to an upper through hole on the mounting bracket, and an auxiliary wheel axle pivotally connected at an inner end to a lower through hole on the mounting bracket and fixedly connected at an outer end to an auxiliary wheel. One of the lifting arm and the auxiliary wheel axle is provided with a small hole while the other one of them is provided with a plurality of adjusting holes. A control assembly can be extended through the small hole and one of the adjusting holes to change a pivotal interval between the lifting arm and the auxiliary wheel axle, and thereby adjust an inclination angle of the auxiliary wheel at each lateral side of the rear wheel.