Affordance refers to the opportunity available to a learning activity. Taking affordance as a theoretical and analytical construct, this exploratory study investigates learners' attitudes and the opportunities WeChat may provide for Chinese cultural knowledge (CCK) learning. The aim is to find out the potential new affordances and compare learners with different language levels. 24 participants were paired with native Chinese speakers and required to complete three-stage activities with the integration of WeChat. This study adopted a mix-method approach. Data were collected through questionnaires, two rounds of semi-structured interviews, chat logs, and WeChat moments. It is found that most learners were positive toward the activities and WeChat provided learners with opportunities for interaction and collaboration, for resource sharing, for knowledge internalization and construction, and for sustainable learning and friendship maintaining. The affordance of knowledge internalization and construction was mentioned with the highest frequency in the interview. The findings that distinguish this study from previous ones are: (1) the affordance for sustainable learning, and (2) differences between high-level (HL) and low-level (LL) learners. In comparison, the activities won more supports from HL learners, and HL learners' frequency in leveraging the affordance for resource sharing and sustainable learning was also higher. Pedagogical implications and research recommendations were provided respectively in discussion and conclusion parts.