The traditional security enforcement approach of network is employing cryptography and authentication scheme. However, we consider that the conventional view of security based on cryptography alone is not sufficient for the wireless LAN and Third-generation (3G) integration networks against malicious or non-malicious insertion of data from internal adversaries or faulty nodes. In this paper, we propose a trust degree-based dynamic model for wireless LAN and 3G integration networks where nodes maintain trust degree for other nodes meanwhile the trust degree is applied to evaluate their trustworthiness. Finally the conclusion is made by verifying the performance of this model through some preliminary simulation results.