Abstract: In Rongcheng county, Shandong province, the best time for artifi-cial rearing of larvae and juveniles of the purple sea urchin Strongylocentrotus nudushas been found to be from July to August. The fertilized eggs develop into young urchins for 19--20 days at 23--24℃. Thelarvae show preference to certain algae for food, among which Chactoceros mulleriis found to be the best in use. And ulva is found to be the best food for youngurchins. The duration of early embryonic development stages is summarized as follows.