To discover the distribution of green algal micro-propagules in the Subei Shoal and clarify the growth of green macroalgae attached on Pyropia aquaculture rafts,an integrated investigation in Pyropia aquaculture area and one cruise in the coastal area of the Subei Shoal were carried out from March to May in 2013.The results showed that green algal micro-propagules were discovered in seawater and sediment during March to May.The average quantity of micro-propagules was 267 ind./L in surface seawater and 43 ind./g in sediment.The biomass of attached green macroalgae increased in Pyropia aquaculture from March to May.Three species,including Ulva prolifera,Ulva linza and Blidingia sp.were found in Pyropia aquaculture rafts.The dominant specie was Blidingia sp.and the second was U.prolifera in spring.This study indicated that the micro-propagules and macroalgae were existed in the coastal area of the Subei Shoal at the early stage of green tide.This was the key point to the governance of green tide in China. To discover the distribution of green algal micro-propagules in the Subei Shoal and clarify the growth of green macroalgae attached on Pyropia aquaculture rafts, an integrated investigation in Pyropia aquaculture area and one cruise in the coastal area of ​​the Subei Shoal were carried out from March to May in 2013.The results showed that green algal micro-propagules were discovered in seawater and sediment during March to May. The average quantity of micro-propagules was 267 ind./L in surface seawater and 43 ind./g in sediment. The biomass of attached green macroalgae increased in Pyropia aquaculture from March to May. Three species, including Ulva prolifera, Ulva linza and Blidingia sp. Found in Pyropia aquaculture rafts. The dominant specie was Blidingia sp. And the second was U. prolifera in spring. This study indicated that the micro-propagules and macroalgae were existed in the coastal area of ​​the Subei Shoal at the early stage of green tide. This was the key point to the governance of gr een tide in China.