Abstract: ：In order to investigate on the therapeutic effect of Shennongshi Chinese medicine powder on PRRS, forty 4-week-old pigs were randomly divided into four groups: negative control group, positive control group, Chinese medicine prescription group 1（2 kg/t）, Chinese medicine prescription group 2（4 kg/t）. Groups 1 and 2 each were added with herb 7 days before PRRSV challenge, and were continuous fed for 14 days. The clinical symptoms and rectal temperature were observed every day, and the body weight was measured regularly. At the end of the experiment, pathological autopsy and lung samples were collected for pathological tissue section observation and score. The results showed that compared with the negative control group, adding traditional Chinese medicine（2 kg/t, 4 kg/t）for 7 days could significantly increase the daily gain of piglets（P<0.05）; The survival rate of piglets in the traditional Chinese medicine experimental group could be significantly improved to 100%（P<0.01）when compared with the negative control group（80%）; After 8 days of challenge, the clinical symptoms were relieved, the body temperature returned to normal, there was no obvious lesion in the lung, but there was thickening of alveolar septum with mild inflammatory cell infiltration, which was not significantly different from the control group（P>0.05）. In conclusion, this study shows that Shennongshi Chinese medicine powder can significantly improve daily weight gain and effectively improve the clinical symptoms and lung pathological changes of PRRSV infected pigs. This study provides an experimental basis for the prevention and treatment of PRRS with traditional Chinese medicine.

Key words: Shennongshi Chinese medicine powder, PRRSV, daily gain, lung lesion