Recently, manufacturing systems are striving for an integrated manufacturing environment. The main aim of this research is to propose methodology and develop a system for generating flexible process plan according to Non-linear process planning approach (NLPP) which is based on a shop floor condition named flexible process plans for all parts before entering the shop floor. Four types of flexibility have been considered which can be related with the part manufacturing. Firstly, sequencing flexibility indicate to the possibility of the sequence interchanging in which required manufacturing operations are performed. Secondly, processing flexibility is refers to the possibility of producing the same manufacturing feature with alternative processes. Thirdly, machine tools flexibility is determined by the possibility of performing an operation on more than one machine and the last is cutting tools flexibility which refers to the possibility of producing the manufacturing feature with alternative cutting tool, the researcher creates mathematical model for each activity of process planning to provide mathematical solution for each one. The developed system basically consists of two modules; firstly, Product design module adopted to define design; secondly process planning module divided into five sub-modules: machining sequence, process selection, machine tools selection, cutting tools selection and machining time sub-modules.