Abstract: In this paper, we firstly use the backstepping method to design the continuous-time state feedback controller, continuous-time observer and continuous-time observer-based controller for a class of nonlinear systems. Then, we obtain the state feedback sampled-data controller and the sampled-data controller based on the continuous-time observer, respectively by discretizing the continuous-time state feedback controller and the continuous-time observer-based controller using zero-hold method. Correspondingly, we employ the Euler method to discretize the continuous-time observer and use the zero-hold method to discretize the continuous-time observer-based controller, then we obtain the sampled-data observer and the sampled-data controller based on the sampled-data observer. This paper proves that the state feedback sampled-data controller and the sampled-data controller based on continuous-time observer can guarantee the asymptotic stability of the closed-loop system. The paper also proves that the sampled-data controller based on sampled-data observer can guarantee that the states of plant are bound, and the boundaries are dependent on the designed parameters and sampling period. Finally, we complete the design of sampled closed-loop system after choosing an appropriate sampling period. An example applied to ship course-keeping control shows that the three types of sampled-data controllers can achieve favorable performance.