【Objective】 To determine the influence of knowledge, attitude, practice (KAP) of the guardians of the floating children to the vaccination of the hepatitis B vaccine. 【Methods】 Three to five districts were chose with relatively more floating population and lower immunization coverage rates as the study location. Also the information about the immunization of hepatitis B vaccine was collected. 【Results】 The knowledge of the guardians of the floating children was poor. 84.3% of them did not know the hepatitis B vaccine being free for newborn infants after 2002 in our country. 64.3% of them knew the effect of hepatitis B vaccine and only 23.8% of the guardians knew the number of HB vaccine doses. The timely immunization rate of hepatitis B vaccine was 70.28%, which was far less than that of the local children. 【Conclusion】 Health education should be implemented to the guardians from various channels in order to improve the hepatitis B vaccine coverage rate among the floating children.