The sea urchin Strongylocentrotus intermedius, which is endemic to intertidal and subtidal bottoms in northern Pacific coastal waters of Hokkaido of Japan, Korea and Far East Russia (Agatsuma, 2013), was introduced into China from Japan in 1989 for its commercial value (Chang et al. 2004).In creasing market demand encourages the development of aquaculture in both Japan and China. The annual production of sea urchins from fisheries and aquaculture in China was 6791 t 2014 (Zhao, 2015) We previously studied the effects ofone generation of inbreeding on fertilization, hatchability and larval development of intermedius, which lays a solid foundation for further studies on multiple generations of inbreeding (Zhou et al., 2013). Thus, intermedius is a good research model to study the effects of multiple generations of inbreedingh. The purposes of the present study are to investigate 1) whether fertilization rate, hatching rate, larval growth and metamorphosis rate are significantly impacted by two generations