The blade has the characteristics of complex structure and many free-form surfaces. In order to solve the problem of preregistration of blade dense measurement data and its CAD model, a six-point optimization localization algorithm was proposed for preregistration. Combining the six-point positioning principle and dock planner must, the original coordinate system is established on the tenon reference plane, and the positioning error analysis and registration is performed on the primary and secondary direction of six-point to reduce the error of each measuring point, so that the CAD model and the theoretical model achieve consistent state. Finally, the six degrees of freedom of point distribution is completed, and the final set of blade model dock planner must control points is obtained. It avoids the tedious calculation of ICP algorithm for processing a large number of point cloud data, and realizes the dense measuring point optimization preregistration of batch blades after six-point optimization positioning, and the positioning accuracy is about 0.02 mm. The registration results of six-point optimization positioning and typical six-point positioning are compared and analyzed. The preregistration accuracy of the six-point optimization positioning algorithm for blades is about 0.02 mm, which meets the accuracy requirements of blade model preregistration.