The bacteria widely distributed in the natural environment and living organisms, they play an important role in nature and human life. They have relationships, interact closely with the host cell and with environmental factors in the function and structure of ecosystems. In Vietnam, the study/of marine microbial communities was few. In particular, no studies on diversity and ecology on marine microbial communities using molecular methods such as PCR-DGGE, FISH... This paper presents some result of application of PCR, DGGE methods and specialized software of Quantitive one - Bio Rad, XLSTAT 2010) in analyzing diverse communities and environmental correlates of bacterial communities in some coastal areas north of Vietnam.