In July 2009, an incident involving a stuck Co-60 source led hundreds of thousands of people to escape Qi County, Henan Province, China, although no medical or environmental consequences were related to the incident. To investigate knowledge about radiation, public risk-perception of radiation, and evaluation of the official response, a survey was conducted in Qi and Hui County (control). Face-to-face questionnaire interviews were conducted among three groups with different educational backgrounds. In total, 1340 valid questionnaires were collected from people interviewed. Knowledge about radiation was low in all groups in both counties, although knowledge in Qi County was higher than that in Hui County (control). More than 40% respondents supported construction of nuclear power plants (NPPs) in China, while only a few supported constructing NPPs in their vicinity. The main reasons for the mass escape following the incident were assumed to be lack of knowledge about radiation, misinformation, the government's failure to disclose information in time and imitation of group behaviour. Over 60% in Group I and II trusted the local government. About 64% disapproved the response of the Qi County government. After the incident, the population in Qi County still knows little about radiation. Although people trust the government, they are dissatisfied with the response of the local government regarding the incident.