This study implemented a training course on robot-assisted language learning (RALL) based on the Technological Pedagogical and Content Knowledge (TPACK) framework for Chinese as a second language (CSL) teachers. The participants were fourteen students from the CSL master's degree program. Content analysis of learning journals and interview was used to be the method to analyze the participants' learning process as well as their knowledge reflection. The results show that all kinds of TPACK knowledge were reflected in the learning journals, especially technological pedagogical knowledge (TPK), technological content knowledge (TCK) and technological knowledge (TK). The participants paid more attention to the strategies of human-robot interaction (HRI) during the course. In addition, participants changed their role from teachers to observers. This study also provides various suggestions of RALL design from the perspective of language teachers.