This paper reports the findings of a qualitative study on a group of mainland Chinese students' multilingual experiences during their cross-border studies in a Hong Kong university from a language ideological perspective. Drawing on in-depth interviews as the primary dataset, the study investigated the language ideologies held by the participants about Cantonese, Putonghua and English. Findings indicated that while the participants espoused a distinct set of language ideologies about Cantonese, Putonghua and English underlying their multilingual experiences in the university, the ideology of language as identity and the ideology of language as commodity emerged as the two major language ideologies. It was also revealed that the ideological tensions arising from the co-existence of the multiple and competing language ideologies resulted in the participants' ambivalences in their use of, and/or investment in, particular languages. Findings also point to the role of the participants' language ideologies in maintaining the social hierarchy of languages within the local language ecology and reproducing the group boundaries between local and mainland Chinese students.