In convergence networks, the different technologies are integrated to offer the pervasive networking. Although it is able to provide better networking ability, the technical differentiation makes the management be more difficult. Especially when the secure issues are considered, it is significant to develop some proper mechanisms for the convergence environment. In this paper, we proposed a secure authentication mechanism for 3G and WLAN integrated network. The proposal is based on TS 33.234, and improves the security with RFID tags.