At the stage of primary and secondary education in our country, the tradition of teaching apprentice teachers has long been maintained by master teachers with rich teaching experience in the form of apprenticeship. This research pays special attention to the construction and improvement of the coaching ability of the master in the practice of "teaching by the master and apprentice". The Shanghai D primary school is selected as a case. Through in‐depth interviews with the master and apprentice, it is found that the construction of the master's coaching ability includes subject teaching, class management and In many aspects, such as professional values, social capital can promote the development of collective abilities and responsibilities based on trusted information and knowledge sharing. Among them, bonding social capital helps mentor and apprentice teachers to break isolation and enhance mutual trust, but it may also lead to homogeneity, exclusivity and bottleneck, while bridging social capital social capital can help mentor and apprentice to obtain additional resources and information, through interpersonal networks and professional learning communities, find opportunities for learning, support, dialogue and other interactions to achieve collaborative innovation.