An apparatus for controlling a radiation therapy device includes a drive module, a control module and an input module. The drive module and the control module are connected with the input module, respectively. The input module is configured to acquire a first arc-shaped trajectory. The drive module is configured to drive a radiation therapy head to move along the first arc-shaped trajectory at a first speed. The control module is configured to control the radiation therapy head to emit rays and form a radiation field, the radiation field includes at least one sub-radiation field, and the first speed is smaller than a preset speed threshold. The radiation therapy head performs a circumferential movement. A circumferential trajectory along which the radiation therapy head moves includes at least two first arc-shaped trajectories, and any two first arc-shaped trajectories are discontinuous.
