It is shown from the analysis results of water depth, shallow seismic section, side scan sonar and bottom sample data that the Kuihua island structure of Liaodong bay has advantageous natural geologic conditions and complex marine engineering geologic environmental characteristics. Although the submarine topography is simple, the sediments is saturated modern marine and terrestrial sediments with characteristics of high moisture content, high liquefaction index, low carrying capacity , etc., and there are many hazard factors including submarine deep scour channel, buried ancient river course, shallow gas formation, etc., which will constitute direct or potential hazards to the marine structures. So, much attention shall be paid to these hazard factors and sedimental characteristics.