Abstract: Dinoflagellates is one of the important harmful algae bloom forming species.Because of the similarity in size and shape,micro-dinoflagellates were difficult to be identified exactly using morphological approaches.Single-cell PCR is probably the most rapid and convenient method that can identify marine dinoflagellates accurately.In this study,Alexandrium tarmarense were fixed with glutaraldehyde,Lugol's solution and formalin respectively.Before undertaken single-cell PCR,the whole genome of single cell was amplified.The results showed that the cells preserved in glutaraldehyde and Lugol's solution could be analyzed using sing-cell PCR in 30 days.While there were negative results in the A.tarmarense cells preserved in formalin.The dinoflagellate Peridinium conicum collected in Lingshui Bay in Dalian were fixed with glutaraldehyde at final concentration of 2%,and successfully identified by combining light microscopy and single cell PCR Amplification methods.