Yearly seasonal influenza vaccination for children 6 months to 5 years of age is recommended by the World Health Organization. However, the uptake of influenza vaccine among preschool children aged (usually ≤ 6 years old) was hardly satisfactory. This PhD study aimed to identify and characterize the factors that influence the decision-making process of caregivers with regards to childhood (6-60 months) influenza vaccination in China and help inform the development of behavioural change intervention to promote the childhood influenza vaccination in China. To conduct this program of research, I employed a mixed-methods approach throughout the study phases, which included: 1) systematic literature reviews on influencing factors of childhood influenza vaccination, 2) quantitative analyses of large-scale population data on determinants of childhood influenza vaccination in three provinces in China, 3) qualitative analyses to explore the reasons for caregivers' perception about influenza and vaccines, and how caregivers perceive and understand the communication on influenza vaccine, and finally 4) a mixed-methods evaluation to explore the influencing factors of healthcare workers’ recommendation for non-EPI vaccines in China. The systematic reviews identified factors influencing caregivers’ decision on childhood influenza vaccination. Using the survey data, caregivers’ confidence in the influenza vaccine, positive influence from healthcare workers, family members, or friends and access to vaccination service were found to be associated with childhood vaccine acceptance. Some caregivers confused the common cold with influenza and thought that vaccines are not effective in preventing the constantly mutating virus. Therefore, targeted efforts should be made to address caregivers’ misperception about influenza and influenza vaccine. Additionally, the communication about vaccines between caregivers and professional information sources, such as healthcare workers, is inadequate. The multi-level ecosystem around non-EPI vaccination should be improved to optimize the communication between healthcare workers and the public.