To cope with the difficulties in planning operating procedures for the process with complicated operational constraints, a model chain based quantitative planning methodology is presented in this paper in which the whole planning problem is divided into two distinct but interrelated sub-problems: determination of operating path and synthesis of primitive operations. A two tier framework corresponding to those two sub-problems is used to describe the methodology in which the top-tier determines the operating path using optimisation methods, and the bottom-tier synthesises the primitive operations through a model based reasoning chain which is achieved based on the following findings: all the operational goals are accomplished by directly or indirectly adjusting the relevant flowrates and/or pressures through some primitive devices such as valve, pump and compressor. The methodology is suitable for quantitative planning of operating procedures when operational constraints are more stringent. A case study is given to illustrate how the methodology is used in a case containing complex mixing constraints.