The invention discloses a fixing device used for automobile processing and a fixing method of the fixing device. The fixing device comprises a supporting device and a main frame; the main frame is provided with auxiliary rods, stop blocks, an operating panel, a lifting turbine rod, fixing rods, buffer springs, fixing plates, fixing grooves and turbine regulating rods; four wheel limiting blocks are arranged, and every two of the four wheel limiting blocks are respectively arranged at two ends of each of two indicating midcourt lines; the lifting turbine rod is arranged at the lower end of theupper end face of the main frame, and is connected by a motor; each fixing plate is arranged on the corresponding fixing rod; the number of the turbine regulating rods is two; the two turbine regulating rods are both arranged on the operating panel, and each of the two turbine regulating rods is connected with the corresponding auxiliary rod; supporting holes of the fixing device disclosed by theinvention are convenient for a user to move a transition bottom plate by using a forklift when the transition bottom plate is convenient to hoist; the wheel limiting blocks are convenient for the userto limit automobile wheels when equipment is operated so as to guarantee safety; the lifting turbine rod is convenient for the user to lift an automobile; and the turbine regulating rods are convenient for the user to move the lifted automobile front and back so as to facilitate automobile processing.