AVNV(acute viral necrosis virus)is the pathogen leading to mass mortality of cultured Chlamys farreri,but the transmission of the virus is unknown.In order to clarify the relationship between the plankton and transmission of AVNV,and to afford proof for tracing transmission track,the sea water samples were fetched from 50 cm and 300 cm depths in the sea area for culturing Chlamys farreri at Shazikou of Qingdao and Sanggouwan of Rongcheng regularly from May to November in 2009,and the plankton was collected by 25 μm,3μm,0.22μm pore size filter,respectively.The AVNV carried by the plankton was identified by FQ-PCR.The results showed that the virus could be carried by the plankton,and the virus number in the plankton from both sea areas arrived at the peak in August.The highest number of AVNV identified for the samples from Shazikou sea area was 8.21×10⁶ copies per litre sea water,and that was 2.98×10⁵ copies for the samples from Sanggouwan sea area.Based on the number of AVNV carried,the plankton group with different particle sizes was 3-0.22 μm,25-3 μm and >25 μm from high to low in turn.The number of AVNV carried by the plankton from 50 cm and 300 cm depths was not different significantly.This is the first report about AVNV carried by the plankton from the sea area for cultured scallop.These results implied that the scallop could be infected by taking the plankton that carried AVNV as food,and the plankton was crucial carrier of AVNV.