Aero-engine blades have a great influence on the overall performance of the engine. Therefore, inspection of the blade surfaces in a rapid and accurate manner has become a key segment to improve the manufacturing quality of blades, as well as the performance and lifetime of the engine. In order to measure the geometrical shapes and dimensions of those workpieces with complex surfaces such as blades in a way of high accuracy and efficiency, the study on application of an optical scanning system in measuring of section parameters of a blade is carried on in the paper. Taking the traditional coordinate measuring machine (CMM) as the system platform, the optical scanning system is equipped with a new laser scanning probe, which is based on the measuring principle of circumferention triangulation. Also, combining with the special data processing software, the system can be used to inspect and evaluate the geometrical parameters of the specified sections of a blade, which could serve as an advanced solution for the shape inspection and quality control of blades. For verifying the application effect of the optical scanning system in the measurement of blade surfaces, a twisted fan blade is selected as the target. In the measuring procedure, 5 sections of the blade are scanned and measured by the system. After the model matching, the errors of profile, centroid position and chord angle on every section are derived, which fully manifests the effectiveness and practicality of the measuring system.