Abstract: A timed-Petri and cubic queue network based modeling method for real-time multitasking systems-TPCQ-is presented in this paper. TPCQ is specially effective in describing a complex real-time multi-tasking system which involves in synchronilation, communication and cubic queue scheduling. The model TPCQ is discUssed and an example of modeling a realtime multi-tasking system in TPCQ is given in this paper.