The scheduling of mixed/batch continuous process plants is difficult since the model and solution have to deal with both discrete and continuous operations. Motivated by the need for the effective scheduling and control of operations in sugar milling, a new type of hybrid Petri nets called Hybrid Time Petri Nets(HTPN) is proposed, which allows the formulation of variable cycle time and variable flow rate in a mixed/batch continuous process. Through analysis of HTPNs models, the feasible schedule and operations for mixed/batch continuous process can be found easily and efficiently. Two smaller problems, which contain the important characteristics of the sugar milling problem, are formulated and analysed by this HTPNs.