Abstract: A multiplex reverse transcription polymerase chain reaction (multiplex RTPCR) was developed for the detection of porcine reproductive and respiratory syndrome virus (PRRSV). Three pairs of primer selected from four pairs were designed based on the sequence of high conservative region of PRRSV. And PCR product was 228, 345 and 490 bp. Diagnostic accuracy of the multiplex RTPCR shown to be 10fold more sensitive than the conventional single RTPCR (conventional RTPCR) method, and the testing time is shorten greatly. Simultaneously, the specificity and sensitivity of this method were evaluated. The result indicated that this assay could reliably differentiate between PRRSV and other swine viral disease, such as classical swine fever virus (CSFV), porcine rabies virus (PRV). The developed multiplex RTPCR in this study may provide a new avenue to the rapid detection of this important pathogen in one reaction, which possess the good character in specificity, sensibility，simple and convenient.