Abstract: Introduction In order to fully exploit and utilize the offshore water's rich wind energy in Guangdong coastline, promoting green sustainable development, soil investigation of site and foundation in the wind farm should be carried out. But offshore investigation is different from the land, and it's very difficult. Method The paper studied offshore wind farm planning along Guangdong coast, technical requirements of investigation and design, offshore site conditions, investigating manners, etc. Result Engineering practice has proved that comprehensive investigation manners should be used under the suitable technical codes and guidelines, and geotechnical data are built based on the basis of offshore wind farm projects. Conclusion The analysis and discussion are reference to offshore soil investigation.