Abstract: The purpose of this study was to construct PRRS-CSF-PCV2 diagnostic DNA microarray. Target genes were chose from PRRSV, CSFV and PCV2 based on their sequences, and corresponding probes were prepared. Then the DNA fragments were spotted onto slide to form DNA microarray. The results showed that the diagnostic DNA microarray can detect PRRS, CSF and PCV2 simultaneously , and can distinguish genotype of PRRSV. The positive standard was formulated as SNR≥1.5 or Intensity≥1 000 based on quantification patterns of total signal intensity and signal Intensity median, respectively. It was high specificity, high sensitivity and reutilization. 20 clinical samples were detected by PRRS-CSF-PCV2 diagnostic DNA microarray. 15%(3/20) , 5% (1/20), 0(0/20) samples were positive for CSFV, PCV, PRRSV, respectively. Co-infection ratios were 15%(3/20) for PRRSV and CSFV, 35%(7/20) for PRRSV and PCV2, 15%(3/20) for PRRSV,CSFV and PCV2.