The feeding and g row th of Japanese common sea urchin, St rongylocent rotus intermedius fed on L aminaria j ap oni ca , Undar ia p innat if ida and Ulva sp. in 10. 0- 25. 0 .. and fed on the mixed algae combined with Sar gar ssum horneri , Chondr us sp. in 15. 4- 17. 8 .. w ere determined respect ively . The relat ionship betw een sea urchin body weig ht ( G ) and test diameter( D) is G= 0. 43132D 2. 9958 . And the results also show e that the daily feeding rates of sea urchin fed on the three kinds of algae are dif ferent and change w ith the water temperature. The daily grow th rates are 0. 5 .. 10- 2- 3. 0 .. 10- 2cm/ ( ind..day) of juvenile sea urchin ( 1. 0- 3. 6cm in test diameter ) fed on L . j aponica, U. p innat if ida and Undaria sp. in 10. 0- 25. 0 .. . T he daily relat ive growth rate is the biggest in 19. 0 .. in the juvenile ( 1. 0cm in diameter) , but in 16. 0 .. for adult ( 3. 6- 5. 0cm in diameter) . The body w eight g row th rate is negat ive of adult sea urchin at 25. 0 .. . For 1. 0 - 5. 3 cm sea urchin, the ability for ant-i hig h temperature decreases w ith the increasing of test diameter. T he color of body and sex gland of sea urchin vary w ith it s fed algae. It also indicates that the sequence of selective feeding on five kinds of alg ae is L . j ap onica, U. p innat if ida, S . hor ner , Chondrus sp. , Undar ia sp. The result of hungry test show s that the sea urchin can be hung ry for 15 days in 21. 6- 27. 4 .. , and the ant-i hungry ability for 1. 7- 3. 5 cm is st ronger than the others of 1. 0- 5. 2 cm sea urchin.