The largestroke linear platform is a complicated nonlinear timevarying system with many uncertainties. Linear active disturbance rejection controller (LADRC) was used to control the internal and external disturbances in the process of the platform motion. The dynamics model of the system was established, and the reason of system nonlinearity was analyzed. A LADRC in which the velocity and displacement of the system were treated as the state variables was designed. The part different from the integral standard system was considered as the total disturbance of the system and it was compensated in the controller. In simulation and engineering experiments, an Scurve and sinusoidal motion planning were applied respectively, to make disturbance rejection tests. The experimental results were compared with the PID control algorithm. At the same external conditions, the results show that the LADRC not only has fast response speed and high precision, but also has strong robustness and good prospects for engineering applications.