As a form of entrepreneurial expertise, effectuation has become one of the most important factors affecting business model innovation(BMI). Existing studies focus on the process and effect of BMI, while the discussion on its antecedents is relatively insufficient, especially the Entrepreneurs’ Cognition. Based On dynamic capability theory, effectuation theory and social network theory, the research constructs a theoretical framework between effectuation and BMI, and discusses the mediating role of external network capability(ENC) and the moderating role of competitive intensity. The survey data analysis of 253 start-ups showed that Effectuation can positively predict BMI, external network capability has mediated effect on the relationship between effectuation and BMI. Competition intensity has a negative moderated effect on the relationship between effectuation and ENC/BMI. The research provides some theoretical support and practical enlightenment for entrepreneurship, and it is beneficial to make decisions and achieve the BMI for entrepreneurs or enterprise managers.