This article explores how Taiwanese immigrants become Australians. Mead’s symbolic interactionism and Barth’s theory of ‘ethnic boundary’ have been employed as the main theoretical frames in this study. The purpose of this article is to re-think the deficiency of symbolic interactionism in discussing the cross-border identity construction of contemporary cross-national immigrants in order to give feedback to that theory and add some relevant communication factors ( such as “host communication competence” ) which will affect immigrants’ identity construction under the context of cross-culture/nation, so that the requirement in researching cross-national immigrants ’ identity could be well met. Extending Mead’s and Barth’s theory in assist with ethnographic observations and in-depth interviews with 65 Taiwanese immigrants in Brisbane, I argue that ethnic identity of diaspora is constructed by the symbolic ethnic boundary which is formed with significant symbols. The Australian community meant paying more attention in appreciating Australian values and life styles such as fair go for all, law abidance, laid back, fever for outdoor activities, respecting personal privacy, independence, friendly and so on. The mainstream media of host country construct cross-boundary identity via interpersonal communication. It meant a tool for immigrants to actively make use of the content of media to build friendship and mutual exchange with Australians. In such interpersonal interaction with host country, the cross-boundary identity was formed stepwise through mutual recognition.