This paper deals with the development of setup planning for Automated FIXture planning system(AFIX) which selects setups, setup sequence and operation sequence in each setup according to the machining mode. In AFIX, part type considered is prismatic workpiece that use the 3-2-1 locating system as the general structure of the fixture. The heuristic algorithms selecting setup and setup sequence are based on DDR(Degree of Dimensional Relationship), AMV(Admissible Misalignment Value) and machining sterategy and feature attributes. A case example is given to illustrate the performance fo AFIX.