Contact type measuring device for online measurement of large forgings and measuring method of contact type measuring device

The invention provides a contact type measuring device and method for online measurement of large forgings. The contact type measuring device comprises a measuring assembly, a moving assembly and a supporting assembly, and a laser range finder and a graduated scale are connected with a first mounting end and a second mounting end in a middle frame respectively. A sliding workbench is connected with a third mounting end in the middle frame through a sliding rail, a telescopic rod and the mounting end of a motor are connected with the first end and the second end of the sliding workbench respectively, an output shaft of a transverse motor is connected with an input shaft of a wheel, and an output shaft of a longitudinal motor is connected with an input shaft of a gear. And the mounting end of the rack is connected with a fourth mounting end in the middle frame. The measuring method comprises the steps of coarse positioning, centroid position adjustment, data measurement and large forge piece diameter acquisitio