The present disclosure provides a ray calibration device and a working method thereof, and a radiation imaging system and a working method thereof, and belongs to the field of radiation imaging technology. The present disclosure can solve the problems that the existing calibration devices have low calibration efficiency and require relatively large spaces. The ray calibration device of the present disclosure includes a driving part, a cam part and a calibration part, wherein the calibration part is located below the cam part; the driving part is adapted to drive the cam part to rotate; and the cam part is adapted to exert a force on the calibration part to enable the calibration part to move into a ray area downwards.