The digital age has fundamentally altered the distribution of work and responsibilities in schools. Parents, as important stakeholders in schooling, are taking on more digital labour and facing changing roles. Before the COVID-19 pandemic, parents' digital labour often remained overlooked as they were not able to observe or participate in the whole process of schooling in the school. However, home-based online learning during the pandemic lockdown has created a rare situation of integrating technology into schooling, expanding parental involvement, and providing an opportunity to systematically explore the digital labour of parents and the influence of parent-teacher power relations in this regard. Using qualitative data from an open-ended parent survey in China, this study finds that parents take on the dual roles of regular parent and "surrogate teacher" in home-based online learning during the pandemic. Behind these two roles is a spectrum of digital labour ranging from technical support, notification delivery, and homework submission to monitoring and guiding school learning, learning content and time management, and learning-related communications with teachers. While technology strengthens existing unequal power relations, it also breaks teachers' monopoly over teaching affairs. Parents thus experience mixed emotions and develop a sense of shared responsibility and empathy with teachers.