Associate with geotechnical engineering problems such as materials classification incompletion,drilling inefficiency,in-situ tests and geophysical methods insufficiency,laboratory soil tests inapplicability and the physical mechanical properties evaluation indicators system establishing,we explore geotechnical engineering investigation technology for atoll cross-sea bridge construction in this paper.Based on an engineering example,we prove that the conventional geotechnical engineering investigation methods play a low efficiency roll during atoll investigations.Finally we summarize that further study for coral reefs geotechnical properties(such as geotechnical environment characteristics,power engineering environmemt,rock and soil composition & description,basic physical mechanics properties,particle breaking characteristics and geotechnical engineering evaluation,etc.) needs to be done,and new investigation technology(such as boring & sampling,geophysical prospecting,in-situ tests and laboratory tests,etc.) for atoll needs to be invented.