As an important style of Earth degassing, volcanic activity is considered to be critical for the research on atmospheric greenhouse gases variation and global carbon budget. Based on the recent advances of research on volcanic gases abroad, the research contents, as well as the research methods including sampling methods and testing methods, are summarized. Furthermore, estimating methods and relevant scales of different degassing styles during quiescent period are discussed. The result shows that on a global scale, the CO2 fluxes during quiescent period of soil degassing, hot spring degassing and fumarole degassing are 105 t/(km2·a), 105 t/a and 106 t/a, respectively. In addition, the total flux of methane from European volcanoes and geothermal areas could reach 104 t/a. Active volcanoes in China are all in quiescent period with area as high as 1.4×105 km2, in which the main degassing styles are soil degassing and hot spring degassing. A broad prospect of research on greenhouse gases estimation for volcanic fields in China could be expected.