Abstract: he turbine blades of an aero engine have complicated surfaces, the reconstruction of which is useful for accuracy analysis and quality control of blade formation. The leaf of a turbine blade is a complicated freeform surface and its fitting is an important step for the reconstruction of the blade. This article presents a B-spline surface hierarchical fitting approach, which includes three steps: constructing a progressive mesh of the surface, parameterizing the progressive mesh hierarchically, and then, fitting the surface based on the progressive mesh through rough fitting, fine fitting, and final fitting. The presented approach can result a higherorder continuous freeform surface. Research shows that the approach is fast and accurate.

Key words: computer application, reverse engineering, surface approximation, triangular mesh, turbine blade