The present disclosure provides a driving mechanism configured to drive a target object to perform a linear motion, wherein the target object includes at least one of a plurality of leaves of a multi-leaf collimator. The driving mechanism may include an output component including an output member. The driving mechanism may also include a transmission component configured to operably connect the output component and the target object. The transmission component may include an output end and an input end. The input end may be operably connected with the output member. The output end may be operably connected with the target object. A linear velocity of the output end may be larger than a linear velocity of the input end.