Setup planning and fixture design are two main tasks for the integration of design and manufacturing process. Setup planning identifies which features must be machined in each setup and determines locating datum for each setup, whereas fixture planning determines precise locating and rigid clamping of workpieces according to a part design and process requirements. So, a close interaction exists between setup planning and fixture design. This research deals with the problems of setup and fixture planning for the machining of prismatic parts. In the first step, a new heuristic method is presented to plan the setups with accurate respect to datum faces in design and manufacturing. Two concepts, namely, "inferiority face" and "control face," have been used for this purpose. In the next step, a mathematical model is used to define the primary, secondary and tertiary fixture planes with respect to locators’ position. This model determines relationship between misplacement of locators and dimensional and geometrical specifications of workpiece. The main purpose of developing the model is to determine the effect of locator height error on hole position tolerance. The capability of this model is verified by simulation in "motion study" module in SolidWorks software. This approach is very useful in the hole-making process. The system is developed in Visual Basic on a SolidWorks platform. The effectiveness of the system is verified by an industrial component.