Abstract: 8 cases of swine co-infected with Porcine Reproductive and Respiratory Syndrome Virus（PRRSV）, Porcine Circovirus Type 2 （PCV2）, Haemophilusparasuis （HPS） were collected. In order to distinguish the difference in pathological between these three pathogens, gross pathology and histopathological were carried out. The results showed that when the swine co-infected with PRRSV, PCV2 and HPS, the gross pathology mainly included with increasing of fibrous exudation in the thoracic cavity and abdominal cavity, systemic lymph node enlargementing and hemorrhaging, consolidation of lung in tip and heart leaf, hemorrhagic spots on the surface of kidney and white spots on the surface of liver. The histopathological changed mainly showed polyserositis, interstitial nephritis, suppurative pneumonia, suppurative splenitis, suppurative lymphadenitis.

Key words: porcine reproductive and respiratory syndrome virus, porcine circovirus type2, Haemophilus parasuis, co-infection, pathological diagnosis