Researched on the intelligent design of built-up fixture, according to the theory of feature mapping and assemble feature, discussed the key technologies and realizing methods within the intelligent design system of feature-based hole-series built-up fixture, such as selecting criteria of process route, determining machining data, reverse-generating of setup planning, method of feature mapping, determining the locating and clamping datum, selecting the components of the fixture and calculating the assembly size of the components of the fixture, etc., brought forward a series of rules and actualizing approach in detail for the design of built-up fixture system, and given a design example of generating a hole-series built-up fixture.