A mobile service robot should have the ability to carry out multiple practical tasks. However, most mobile mobile service robots have been designed to carry out a specific task. Hence it has been difficult to design a navigation framework for multiple navigation tasks. In this paper, we will design and implement a navigation framework for multiple tasks using the GSPN (Generalized Stochastic Petri-Nets). The GSPN-based navigation framework has several advantages, such as performance analysis and dynamic system analysis. Furthermore, such a design can process system events in realtime. Also, the typical problem of a hybrid control system, namely the synchronization and scheduling between reactive layer and high-level planner can be solved using the GSPN's event monitoring ability using the timed transition and immediate transition. Finally, the idle time and activation time of the tasks can be predicted under the GSPN-based navigation framework. In this paper, firstly, the transportation task and patrol task are implemented. Then, a navigation framework is designed using the GPSN. The proposed GSPN-based navigation framework is verified in the human co-existing environments by experiments. The results showed that the proposed navigation scheme can be used practically in real environments.