Abstract: Purpose/Significance To understand the factors influencing the formation of online public opinions on pre-published public policies, this paper is to provide research implications for policy-issuing institutions to guide the public to express their opinions and promote the scientific policy-making process. Design/Methodology Taking online opinions of three pre-published public policies as examples, this study analyzes the influencing factors of online opinions formation by using the grounded theory to code online comments. Based on social cognition theory, the influencing path and formation mechanism of online opinions on pre-published public policies are constructed. Conclusions/Findings The results show that the online opinions on pre-published public policies are affected by five factors, the public, policy, government, media and environment. This paper makes a thorough analysis of these five factors and further puts forward some strategies and suggestions to guide rational expression of online opinions.