An automatic collimator adjustment device and method for medical treatment equipment are disclosed. The medical treatment equipment includes an automatic collimator adjustment device, which includes a processor unit, a depth camera, and a collimator control device. The processor unit receives an instant image pixel depth signal acquired by the depth camera to compare with a predetermined image pixel depth signal of a predetermined human body portion of a target human body in order to generate at least one collimator adjustment signal to the collimator control device, so that the collimator control device controls the collimator to adjust the X-ray beam to align with the predetermined human body portion of the target human body.
