Abstract: With the further development of marine exploration in China in recent years, higher requirements are put forward for the capacity of the soil and cyclic loading effect for the offshore engineering. Due to the difficulty and high cost of laboratory tests which the samples are collected from the deep water, marine geotechnical engineering often relies on the in-situ testing technology. The development of offshore CPT technology is reviewed, and a kind of full-flow penetrometer is introduced for marine soft soil. The theoretical and experimental researches on the full-flow penetrometers of domestic and foreign scholars are summarized, including the relationship between penetration resistance and soft soil undrained shear, evaluation of the characteristics of remolded soil from cyclic penetration tests and numerical simulations of resistance coefficient of T-bar full-flow penetrometers. Finally, some suggestions are put forward for the development of full-flow penetrometers.