The invention discloses a telescopic arm mechanism of a car puller, comprising an engine base, a crank, a connecting rod I and a car pulling arm, wherein the crank is fixedly connected with a point A of a drive shaft and is articulated with the connecting rod I, the connecting rod I is articulated with the car pulling arm which is supported by a front guide wheel and a rear guide wheel, a brakingroller wheel is articulated with a swing arm, the swing arm is articulated with the engine base, a connecting rod II is respectively articulated with the swing arm and an A I section of the crank, and the A I section is synchronous with the crank. When a barycenter of the car pulling arm is positioned between the front guide wheel and the rear guide wheel, a slider-crank mechanism comprises the engine base, the connecting rod I, the car pulling arm, the front guide wheel and the rear guide wheel to realize the telescopic movement of the car pulling arm, and the connecting rod I and the car pulling arm are arranged on the crank; and a brake connecting rod mechanism comprises the engine base, the crank, the connecting rod I, the car pulling arm, the front guide wheel, the rear guide wheel, the swing arm, the connecting rod II and the braking roller wheel to realize the luffing motion of the car pulling arm.