The seasonal regularity of strobilation of edible medusa, Rhopilema esculenta,hasbeen observed for three years, the medusa were reared in three different kinds ofhabitats, i. e. the natural sea inlet, the indoor concrete tanks and aquaria in labora-tory. This paper deals with the content about the season of occurance, velocity of pd-eveloment, frequency of repetition of strobilation, number of ephyrae produced andthe development of abnormal strobila of the medusa.The strobilation begin to occur in spring each year when the water temperaturerises up to 13℃, then ephyrae are released at above 15℃. The samo individual canstrobilize repeatedly 6-13 times from the beginning of strobilation in spring to the endof antumnwhen the water temperature falls below 15℃. The first time of strobilationoften produce 5--14 ephyrae. In the course of repetition of strobilation, the number ofephyrae formed each time gradually decreases. The strobilae occurred in summergenerally only poosesses one or two segments. The average developmental period inproducing an ephyra is about 2.1 (i. e. 1-4) days. The shortest and longest intervalsbetween two periods of strobilstion are 3 and 28 days respectively, but generally isabout 10 days. The abnormally developed strobilae can be divided into many categories,i. e. develo pment in deficiency, development in stagation, development in reverseand develo pment in both ends.