Qinzhou bay. The condition of becoming an oyster breeding base is abundant phytoplankton. According to the information on the Internet, Qinzhou Bay has the middle and lower reaches of the inner bay where rivers flow, or the sea area not far from the estuary. The sediment is silt, sediment, sand mud or rock, with gentle tidal current, fresh and pollution-free water and excellent natural environment. It has been the natural habitat of giant oysters since ancient times. The annual salinity of seawater in the culture area is 13.04-32 ‰, and the salinity is moderate most of the year, and the time when the salinity is below 7.52‰ in flood season is within the tolerance range of oysters. The exposure time of dry tide shall not exceed 4 hours. The monthly average annual variation of water temperature is between 10-30, and the duration of low temperature below 10℃ and high temperature above 30℃ is not long. The transparency is 0.25-2m. The pH value is 7.5-8.33. The tidal current has a large wave difference, with a velocity of 0.3- 1.5m/s, and the tidal current has the characteristics of reciprocating flow.