The invention provides a linear control method for a segmental beam with a specially-shaped cross section through a short-line pedestal matching method. The linear control method comprises the following steps of establishing a plurality of control measuring points on each beam section; calculating the distance between the control measuring points at the positions A of a prefabricated beam section and the control measuring points at the positions B, corresponding to the positions A, of a matching beam section; performing calculation to judge whether the difference between an actual measuring distance and a preset distance of the control measuring points at the positions A of the prefabricated beam section and the control measuring points at the positions B, corresponding to the positions A, of the matching beam section meets the accuracy requirements or not; and if not, readjusting the beam sections to perform accurate positioning. The linear control method disclosed by the invention has the advantages that the prefabricated beam section and the matching beam section are accurately positioned, so that the beam shape of the next beam section is guaranteed, and assembling of the next beam section and the previous beam section can be performed smoothly.