Abstract: To investigate the dynamic changes of WSSV (white spot syndrome virus) carried by Microcystis aeruginosa and Chlorella pyrenoidosa and their effects on WSSV amount in water, we added the same WSSV amount to high-density groups, low-density groups with those two microalgae and compared them with the control group without microalgae, then determined the WSSV amount in supernatant and precipitate algae by TaqMan real-time PCR at 2^nd hour, 24^th hour, 72^th hour and 120^th hour. Results show that both M.aeruginosa and C.pyrenoidosa carried WSSV but the amount decreased with time. The WSSV amount carried by M.aeruginosa was significantly positively correlated with the density of algae cells (P < 0.05), while there was no significant correlation between the WSSV amount carried by C.pyrenoidosa and the numbers of algae cells (P>0.05). Both the two microalgae reduced WSSV amount in water, and the reduction effect of C.pyrenoidosa was better than that of M.aeruginosa, which is beneficial to the ecological prevention and control of WSS (white spot syndrome).