【Objective】The present study was conducted to learn the oyster larvae quantity dynamic in Shajing， Maowei Sea of Qinzhou Gulf in order to improve the effect of oysters collecting. 【Method】The gonad maturity was identified and the oyster larvae quantity was calculated in Shajing， Maowei Sea of Qinzhou Gulf while the data of water temperature， salinity， pH and the weather condition were collected. 【Result】The results showed that one breeding peak of mature oysters in Shajing was observed from 25 June to 3 July in 2011 when the water temperature （down 3.0℃）， salinity and pH （down 0.97） of seawater （down 4.0‰-8.0‰） decreased sharply. Five hatching peaks appeared on 21 May， 17 June， 1 July， 12 July and 18 July， respectively. The oyster larvae quantity of the above dates was 2.87×104， 2.13×104， 1.94×104， 11.94×104 and 1.69×104 /m3， respectively. Oyster larva preferred to gather in the depth of 0.5 m than 2.0 m. The larva quantity dynamic was affected by the quantity of mature oysters， its hatch time and hatch quantity as well as the tide and ocean current. 【Conclusion】The oyster larvae quantity dynamic in Maowei Sea is directly related to the gonadal maturity of mature oysters and the environmental factor in sea area.