In this paper, we adopt the Particle_in_Cell(PIC) program to study the transverse movement of particles in high_intensity beam. It is found that the transverse movement of halo particles in not always in halo region. The movement is restricted in a narrow region after the beam is controlled. Changes of root_mean_squared radius are nearly periodic. According to the regulation and variation of root_mean_squared radius, a new self_adaptive controller method is put forward. This research demonstrates that the halo can be completely controlled by the controller quickly. There is no need to precisely calculate the coefficient of controller, and the controller can work well even if the system parameters are changed.