In order to study the anti-porcine reproductive and respiratory syndrome virus (PRRSV) effect of spider fragrant extracts,a Marc-145 cell model was established,and ribavirin was used as a positive control drug.By observing cell lesions and MTT colorimetry,on the basis of the maximum safe concentration of the extracts of Valeriana jatamansi Jones on Marc-145 cells,the water extract and the alcohol extract of Valeriana jatamansi Jones groups,a ribavirin positive control group,PRRSV and cells control group were established.In the control group,PRRSV was blocked,inhibited and directly inactivated.The results showed that the highest inhibition rates of the extracts of Valeriana jatamansi Jones on blocking and inhibiting PRRSV were 44.6% and 37.9%,respectively,which was significantly(P<0.01) lower than that of the ribavirin positive control group,and the cells appeared more obvious lesions.The highest inhibitory rate of the blocking and inhibition of PRRSV by the alcohol extract of Valeriana jatamansi Jones group was 107.1% and 102.6%,respectively,which was significantly(P<0.01)higher than that of ribavirin positive control group,and the cell morphology was basically intact.The highest inhibitory rates of the water extract and the alcohol extract of Valeriana jatamansi Jones groups on the direct virus inactivation were 83.5% and 120.9%,respectively,which were significantly higher than those of the ribavirin positive control group(P<0.01).It can be seen that the spider mellow extract has a strong anti-PRRSV effect.