The paper presents a speed sensorless of permanent magnet synchronous motor(PMSM) using nonlinear control method. A novel cascaded sliding mode observer is proposed to estimate speed and rotor position, which overcomes the time delay caused by the low-pass filter. A front current sliding mode observer that estimates the EMF of the motor in the axis, a back EMF sliding mode observer that estimates the speed and rotor position, the Lyapunov theory is used to prove the stability of the algorithm. For the speed control problem, a robust sliding mode control with extended state observer (ESO) is designed to improve the robust performance of system. To reduce chattering of the system, hyperbolic tangent function is employed to substitute for sign function in the sliding mode observer and controller. This method is used to PMSM vector control system, Simulation results are presented to verify the effectiveness of the proposed observers and controller.