Friction exists in a wide range of physical systems. On the other hand, deadzone hysteresis nonlinearities seem inevitable in practice especially in mechanical system. In this paper, a class of mechanical systems with dynamic friction and unknown deadzone hysteresis are considered . A state feedback control scheme is proposed by using backstepping techniques. In this control scheme, an approximation of deadzone model is constructed and we use a linear part and a bounded part to approximate hysteresis input. The stability of closed-loop system and output tracking performance can be ensured by this control law and update laws of unknown parameters and the upper bound of external disturbance.