Taken the plastic shrinkage of 921A quenched and tempered high-strength alloy steel under the influence of heat conduction temperature field as the main research object, the typical partial ship structure is selected to conduct the demihull test, and the data measurements are taken in combination with the section construction technology elements. The data treatment is given, the shrinkage and shrinkage factor of 921A steel during the construction are determined and converted into the corresponding precision addition factor to obtain the precision compensation finally, which can provide a basis for the precision control of actual hull structure construction planning and design.