The invention discloses a method for controlling laser peening correcting shape precision of an aero-engine bracket on line. The method comprises the following steps of (1) detecting the outline of a welding bracket, and measuring deformation amount and residual stress near a welding region and nodes through a three-dimensional shape measuring system; (2) inputting measured data into a large data platform, wherein welding nodes with different structures are divided in comparison with an existing designed structural scheme, and deformation types of the welding nodes are respectively analyzed; (3) according to different divided types, calculating shape precision errors of bracket tube units of deformation node regions, determining needed correcting amount, planning sequence for correcting the deformed regions and determining the optimal correcting scheme; (4) correcting the deformation nodes of the aero-engine bracket according to the optimal correcting scheme, carrying out shape detecting on the corrected modes through a three-dimensional shape measuring instrument, and inputting data into the large data platform; and (5) evaluating the correcting effect through the large data platform, determining whether secondary correcting is needed or not, repeating steps (1) to (3) if needed, and approaching step by step until the designed needed shape precision is reached.