Gas-tight sampling techniques of seafloor sediment are very important for various ocean researches, for the realizations of research goals are closely linked with the in-situ information of sediment samples. The purpose and significance to develop seafloor gas-tight sampling techniques are discussed in this paper, along with the definition of the gas-tight sampling techniques and the development of the seafloor pressure samplers. Several major techniques of the gas-tight samplers are emphatically presented. The development of the gas hydrate pressured corer in China is also introduced. Several ideas about how to develop gas-tight sampling techniques in China are put forward: 1) attach importance to the low-disturbing sampling research, and offer level clarity and material composition complete sediment samples for relevant oceanography research; 2) similar to the HYACINTH, in order to meet different geological conditions of seafloor, develop the series of gas-tight sampling devices. The gravity or shake corer can be adopt for the soft sediment (from the ooze, sand to gravel), and the rotary corer for the hard sediment; 3) carry out the core transfer technique under pressure. realize the analyzing, storing and obtaining of the small section samples without loss of pressure in laboratory, and launch geophysics, geochemistry, microorganism, and petroleum physics researches under the in-situ conditions; and 4) launch large depth sediment sampling technical research, and provide technical support for gas hydrate research in China.