Utilizing integrated satellite-terrestrial cooperative systems is one of the new fields in cooperative communications that allows us to use both of the systems privileges. In this case disadvantages of each system will be compensated by another system. Channel modeling of the satellite communication has always been one of the main problems in this field and for many years, theoretical performance of the proposed channel models, was not consistent with the observed experimental results. These years a more realistic multi-state channel model has been proposed in which the channel coefficients are varied by changing weather or user environmental conditions and transition from one state to another one is occurred in the channel model. In this thesis, after introducing the terrestrial and satellite channels, the performance of satellite-terrestrial cooperative systems is analyzed and simulated using multi-state satellite channel. The results is compared with non-cooperative scheme. Also the simulation results are compared with approximated analytic bit error rate results using K modulation. The results show that using cooperative relaying system in urban environments is necessary for improving the performance of the system. In these environments, the performance of single relay system with small relay power is very similar to the performance of non-cooperative system in an open space environment condition. Keywords : atellite-Terrestrial Cooperative Systems, Multi-state Channel, Markov Chain, Cooperative/Relaying Communication