The work of breeding bay scallop seedling has been studied in the past. The breakout of the brown tide in Hebei Area has brought significantly negative effects on the industry of bay scallop. To avoid the outbreak, the breeding of late seedling (parents bay scallop were put into seedling rearing room for breeding at the be beginning of April) and a chain of experiments concerning to bottom sowing culture in pond and longline aquaculture were carried out during 2012−2013. The results showed that the average shell length was 59.7 mm for the late seedling (with shell length 5.0−6.1 mm) after bottom sew into pond in June 2012 for 139 days cultivation. In 2012, after a longline aquaculture, the average wet weight, scallop adductor weight and adductor output rate of the late seedling were 28.7 g, 3.8 g and 13.8%, respectively. In 2013, after a longline aquaculture, the average shell height, wet weight and scallop adductor weight were 50.3 mm, 24.4 g and 3.1 g, respectively. The data suggest that the aquaculture of late seedling may reduce the expenditure of 45.5 t coal and 67.5 thousand Yuan per 1000 m3. These results also suggest that the planned delay may help to efficiently avoid the adverse effects of brown tide and may serve as a reference to the development of the whole bay scallop cultivation industry.