On the basis of induction phenomenon during gas hydrate formation,the definitions of induction time developed according to different theories,were summarized and analyzed by means of the micro and macroconception.The relationship between induction time and other time intervals was further examined,and the induction time for special situation was also introduced.In order to measure the induction time easily and make a clear definition of induction time be taken as an effective way to judge the promoter or inhibitor in application,it is suggested that the induction time can be defined as the time interval from the reaction beginning to the moment that one parameter of the system changes sharply,i.e.from the start of the hydrate reaction to the moment that the abundant detective nuclei appear.In this way,the induction time can be connected with some of the measurable parameters,which makes the definition of induction time more practical and applicable.It is expected that an unambiguous definition of induction time when used as an effective criterion will have an active effect on the development of storage and transportation industry of the gas hydrates as well as some relative technical field.