In this paper, an approximate method for estimating the performance of the synchronization stations of an Extended Kanban production system is developed. The correct treatment of an Extended Kanban system requires the decomposition of the system into a set of subsystems and the coupling of the synchronization stations of each of these. Unlike other Kanban type systems, the analysis in isolation of each synchronization station gives inaccurate results due to the simultaneous arrival of requests at all stations. The method of coupling of the synchronization stations of each production stage which is proposed, gives a good approximation of the performance of the production system, and makes the process quite accurate. This method provides a good basis for the comprehensive analysis and solution of a system of Extended Kanban.