Drawing upon Frenzel's (2014) framework of appraisals, the current study explored language teachers' emotional experiences and their antecedents in the online teaching context. Moreover, the interrelations between teachers' emotions and their instructional practices were also investigated. Data were collected through semi-structured interviews with eleven language teachers from a top-tier international university in China. Our findings revealed that positive appraisals of online classroom events, including goal attainment, the capacity in and responsibility of effectively delivering lessons online, and the importance teachers attached to online teaching, tended to result in positive emotional experiences, which consequently led to motivational stimulations in more creative and productive instructional practices. By contrast, teachers who had negative appraisals of online teaching events tended to experience more unpleasant emotions and emotional vulnerability, which would possibly impede effective instructional practices and steer their teaching towards more traditional teaching methods. Our study contributes to the understanding of the relations among teachers' appraisals of classroom events, emotional experiences, and instructional practices in online language classrooms. Implications for how to prepare teachers emotionally for online teaching are also discussed.