Abstract: Eggs of Chinese native brine shrimp,Arte mia solina,were simply packed in oblate plastic capsules and then carried by satellite "8785".The total dose of ionizing radiations received by the eggs during 5-day spaceflight was about 150 mrads.The flown eggs started to be incubated in artificial sea water and observed,along with ones of earth control,on 8th,21st,24th,34th and 66th days after accomplishment of the flight.Main phenomena found were as follows: (1) A significant delay of emergence and hateching occurred in flown eggs.(2) The extent of this delay appeared to have reduced gradually during prolongation of egg storage at 4℃.(3) Reduction of rates of emergence and hatching was also seen in the flown eggs,and it was going more and more serious during prolongation of the egg storage.(4) The survival curve,within 23 days,of larvae hatched from flown eggs was very similar to that of ones from earth control eggs.A "developmental barrier" and a "critical level" of agg damage were supposed in explaining the phenomena.