The invention discloses a method for controlling the manufacturing precision of a super-long T-shaped cross beam of a steel truss girder, which comprises the following steps of: formulating a partitioning scheme, dividing a large cross beam into a plurality of sections of small cross beams, controlling the length of a single small cross beam
not to exceed 9m, and arranging a butt-joint groove at the joint position of a web plate and a
flange plate of each small cross beam; modeling and
lofting are carried out, a web plate and a
flange plate are sequentially taken out, a process adding amount is set on the bolt hole side of the small cross beam, and meanwhile the width adding amount of a U-rib notch is set; assembling a small cross beam web plate and a
flange plate by taking the
base line as a reference, and determining an assembling precision control target; and designing an overall
assembly scheme of the large cross beam, optimizing a structure
welding sequence, formulating pre-arching process parameters, and finally realizing a precision control target. The method is not influenced by the length rolling capacity of the steel plate, can adapt to
machining precision control of the orthogonal special-shaped plate in the steel structure bridge, has universality, is generally used in various steel structure
machining factories, is high in precision after being manufactured, reduces a large amount of repair work, and can obviously improve the construction efficiency.