In order to increase and control interactive for the system of hyperlink-application, this research tries to apply Petri-Nets to analyze and control the instructional flow on Web-based platform. Petri-Nets is both a mathematical and a graphical modelized system analysis and development tool. It is well suited for the analysis and control of the system having the dynamic data flow properties. Applies Petri-Nets to the flow control of the instructional presentation is a deep revelation for the hyperlink being one kind of useful method to provide the interactive-instructional on the Internet/Intranet.