Abstract: The Xuwen Area covers 7403km² (in which sea area is about 3870km²)and includes the southern Leizhou peninsula of Guangdong Province and its west and east sea area, most of Qiongzhou channel and northward part of Haikou city, Hainan Province.Natural geog raphic conditions are hard with semitropical perennial high temperature and rainy climate, and terribly poor field working conditions with storm waves and big tide fall in sea area.Based on lit tle basic geologic data of discovered oil/gas bearing sag of Beibuwan Basin, this article summarizes play forming rules of the basin as theory directions, puts forward the research results of structure unit classification, boundary faults and inferential sedimentary zone; and give primary appraisement on potential perspective districts by means of the analogic oil/gas geologic conditions.