Objective: This study focuses on the students’ different decisions on vaccination caused by the contexts of college environment and aims to use qualitative method to investigate how different fields affect students’ decisions. Methods: This study uses Semi-structured interview to collect materials and Grounded theory to analyze the materials. Results: By comparing two typical cases, Class A and Class B from a same school of a university but with drastic different HPV vaccination rates (87.5% and 0 respectively), this study found that conventional factors such as knowledge about disease, and price of vaccine could not explain the huge large gap between the two groups. Instead, a class will form a vaccine-favorable or vaccine-unfavorable field because of differences in information transmission, class atmosphere, as well as curriculum design, and then leads college students to make different decisions on vaccination. Conclusion: Contrast found that filed with flexible time, harmonious atmosphere,communication habits and authoritative media will promote college students to make vaccination decisions. KEY WORDS: College Students, Vaccination, HBV, Field