The physics performance of thin-walled rotary parts made of hard brittle material on high-speed aerocraft cannot meet the technical requirements after semi-finished processing, in order to compensate the physics performance, the wall thickness should be properly grinded based on the inner surface reference in the finish machining. A processing method consisted of measuring, calculating and grinding functions is investigated. The data of complex surface is obtained with trigger measuring technology, and the reconstructed profile is calculated with cubic polynomial approaching algorithm, which has fast and stable merits in suit with efficient machining. The grinding G program is generated according to the concrete construction of machining tool. This method has been verified by experiments.