The invention provides a shafting alignment displacement optimization method and belongs to the technical field of ship propulsion shafting alignment. In order to ensure continuous and reliable operation of a shafting, reasonable alignment needs to be carried out on the ship shafting. In a reasonable alignment process of the shafting, a shafting layout state is found; various bearing loads, bending moments of various shaft segment sections and pivot point rotation angles are located in a reasonable state; the shafting state is expressed through an engineering language; corresponding shafting alignment regulations are provided for onsite constructors; and the onsite constructors mount the shafting in an ideal state according to construction technological regulations and carry out alignmentquality detection. Compared with the traditional method for carrying out debugging manually according to experiences, the method has the advantages that the efficiency is higher, the precision is higher, the popularization is easy and required manpower is less and material resources are fewer. The whole operation process is relatively simple, a mounting and alignment period is greatly reduced, theshipbuilding cost is reduced, and the competitiveness of a shipbuilding industry is improved.