This paper deals with the study of breeding habits of the edible jellyfish (Rhopi-lema esculenta) in Hangzhou Wan Bay from 1978 to 1981. The results are sammarizedas follows: The edible jillyfish is a large coelenterate. its reproductive organ is gonochoristic.The gonads attach inside the membrane of stomach cavity which locates under theumbrella. The ripe egg is roundish, the sperm is triangular with a long-tail. Thecourso of maturity may be divided into four stages: the early stage, developing stage,apawning stage and post-spawning stage. The developing character of the egg mothereells is unsynchronous. The fecundity of this jellyfish is very high. The egg amountranges from 220×10⁴ to 6,700×10⁴ (3,000×10⁴ in average) when the umbrella dia-meter of the jillyfish reached 23--53cm. The egg amount increases along with theincrease of umbella diameter. The spawning period of the jillyfish is quite long inHangzhou Wan Bay. It may be taken three months from Sept. to Nov., but thepeak period of spawing is in Sept. and Oct. when the water temperature reaches to22--26℃.