This paper examines a cohort of Chinese preservice teachers' (PSTs') (n = 13) international teaching practicums (ITPs) experiences in Canada from the perspectives of complexity theory and boundary-crossing. Through semi-structured interviews and reflective journals, we positioned PSTs' ITPs within multiple layers, including biographies, the Chinese and Canadian teacher education programmes, the Canadian university setting, K-12 schools, and the different socio-cultural milieus. Through the lens of boundary-crossing, we categorised PSTs' ITPs into four categories: identification, coordination, reflection, and transformation. This article enriches our sophisticated understanding of the non-linear and multi-level nature of the PSTs' professional learning during the ITPs.