A general methodology for mission reliability modeling and analysis of space TT&C system using DSPN was proposed to evaluate the TT&C scenarios.By dividing the time sequences of TT&C mission profile and taking into consideration of the complex situations which were difficult to be dealt with by other modeling methods such as phase dependency of TT&C units

reparability of the system and different time intervals for various TT&C units

the mission reliability of TT&C system was modeled by "component-system logic-phase " three levels of Petri nets (PN) that could interact with each other.After simulating the DSPN model

the quantitative assessment mission reliability of TT&C system for given TT&C scenario can be obtained.The case study reveals that the simulation results have a good convergence with the increase of simulation numbers

and the errors are controlled with one percent compared with the analytical result of Markov analytic method.