The invention discloses a movement synchronization system and a movement synchronization method of a lower limb rehabilitation robot based on treadmill training, and relates to the technical field ofrobots. The movement synchronization system of the lower limb rehabilitation robot based on treadmill rehabilitation training comprises a suspension device, a lower limb orthotics device and a treadmill, wherein the suspension device is connected to the lower limb orthotics device; and the lower limb orthotics device is connected to the treadmill; the movement synchronization method of the lower limb rehabilitation robot based on treadmill training comprises the following steps: within a cycle, synchronizing movement speed of the lower limb orthotics device with the treadmill; and at some moment, synchronizing movement speed of the lower limb orthotics device with the treadmill. The movement synchronization system and the movement synchronization method provided by the invention have the advantages that a patient, who undergoes gait training, can be prevented from getting fallen, so that a better rehabilitation effect is achieved and a rehabilitation progress is accelerated.