This paper employs the grounded theory method to explore impacting factors of knowledge sharing by online knowledge sharing networks users with the moderating effect of communication visibility, aiming at facilitating healthy and sustainable development of online knowledge sharing networks, facilitating knowledge sharing and innovation practice. The interview outline was designed according to the research topic and data were collected by in depth interviews. Three levels of coding were used to develop a theoretical model and the saturation was verified. During open coding, 495 initial concepts were firstly elicited, and then 29 basic categories were elicited by categorization. During axial coding, 14 main categories were elicited based on basic categories. During selective coding, knowledge sharing was identified as the core category. It is found that social capital, social cognition, psychological empowerment, face, time pressure, perceived enjoyment, privacy concerns, others' knowledge need, knowledge sharing topics and personality traits have direct impacts on knowledge sharing with the moderating effect of communication visibility.