Method and system for positioning structure in cofferdam

The invention discloses a method and system for positioning a structure in a cofferdam, and relates to the field of bridge construction, and the method comprises the following steps: determining a feature point of each to-be-measured direction on the structure; and correspondingly calibrating two axis points of which the connecting lines are parallel to the axis of the structure at the two ends ofthe top opening of the cofferdam based on the feature points in a to-be-measured orientation; erecting an observation device on the plumb bob surface passing through the two axis points on the top ofthe bearing platform; by taking an axis point corresponding to the to-be-measured orientation as a reference, establishing a working baseline, taking the working baseline as a reference, keeping thehorizontal angle of the observation device unchanged, adjusting the vertical angle to observe the horizontal ruler placed on the feature point, and reading scales on the horizontal ruler. reading thescales on the horizontal rul