Abstract: [Objective] To develop multiplex PCR method for detection of classical swine fever, porcine reproductive and respiratory syndrome, porcine circovirus type 2, Streptococcus suis, Haemophilus parasuis, swine Pasteurella multocida and swine Mycoplasma hyopneumonia. [Method] Seven pairs of specif/c primers were designed for two multiplex PCR based on the conservative nucleotide sequences published in GenBank. After optimizing reaction conditions, sensitivity and specificity of two multiplex PCR methods were evaluated, respectively. [Result] The genomic DNA of other common pathogens were not amplified by the two multiplex PCR methods, and the detection limit of the two multiplex PCR methods was at a picogram level of genomic DNA or cDNA. [Conclusion] The two multiplex PCR methods can be used for diagnosis of single infection or mixed infection of above seven pathogens.