The invention discloses a method for positioning butt joint of two total sections in large dock shipbuilding. The method comprises the following steps: firstly, measuring the following data of the butt joint surface of a first total section: a molded breadth or molded depth measuring point (P1), a deck centre measuring point (P4), each measuring point (P3) of an outside plate of a bilge, centre measuring points (P5) of an inner bottom plate and an outer bottom plate, and points (P2) for measuring heights from each break angle of an inner shell plate to the centre and a base line; and secondly, feeding the data back to a second total section so as to provide positioning reference data for the subsection positioning at the close seam when subsequently positioning the second total section. In the method, in order to reduce cutting and repairing work, a set of positioning process requirements on the subsection at butt point close seam of the two total sections in the large dock shipbuilding is provided, which realizes the butt joint of the two total sections effectively, improves work efficiency, and reduces working cost and working difficulty.