The invention discloses a construction method for an indoor long-span steel connecting bridge, which comprises the following steps: (1) installing a fixed support, and setting up a supporting jig frame; (2) dividing a main beam of the steel connecting bridge into at least two sections, and respectively cross hoisting the at least two sections to the fixed support and the supporting jig frame; and(3) welding the sections of the main beam of the steel connecting bridge to be a whole. By using the method, the construction difficulty of a steel connecting bridge can be reduced, and the construction period is shortened.