Some key parts used in such area as the national defence are made of high performance hard and brittle materials, and they should meet not only the requirement of geometry accuracy but also that of specified physical performance in manufacturing. The Radome is one of such key parts in the active homing guidance weapon, with a typical complicated surface. In order to meet the electric thickness requirement, a controlled removal grinding point-by-point is needed for the radome during its precision machining. A special 3-coordinates equipment with spherical diamond grinding wheel is adopted; the grinding paths are generated in the planes normal to the cutter axis with a Z-level profile machining method; the feed step is determined by step screening method; and the stepping between layers is carried out according to the remaining scallop crest height. Process conditions including the grinding depth and the workpiece speed are determined through experiments, and the process errors under different processing conditions are analyzed to put forward an optimized processing tactics. As a result, a basis for precision removal process of any other part of high performance hard and brittle materials with complex surface is established, and a technology support for precision machining of key parts in the national major projects is provided.