The invention relates to the field of medical instruments, in particular to a clinical fixing device for severe medical treatment. The device comprises a fixing seat, a horizontal support part, a clamping assembly and an angle adjustment plate. The device can fix the patient's limb by adjusting the angle adjustment plate to a horizontal state or achieve the fixation of the angle, knee, wrist and elbow joint of the patient at different angles by adjusting the angle of the angle adjustment plate; the device can help patients recover well, and adapt to patients of different body types; and meanwhile, the angle of the overall body of the device can be adjusted. The upper end of the base is fixedly connected with a support column, and the lower end of the support column is fixedly connected with a fixing ring. The outer ring of the fixing ring is fixedly connected with an insert sliding sleeve, and the front and rear ends of the base are in threaded connection with two fastening screws I; the front and rear ends of the horizontal support base are fixedly connected with two jaw sliding sleeves, and the upper end of the horizontal support base is fixedly connected with four vertical support rods.