Total community DNA was extracted and purified from soils contaminated with different levels of mixed heavy metals by FastPrep ®system, and then amplified by using eubacterial 16S rDNAs primers.Their PCR products were analysed by DGGE to obtain bacterial community patterns.The results showed that the FastPrep ®120 instrument with the FastDNA SPIN Kit for soil can be used to rapidly, effectively extract and purify DNA from polluted soils.The electrophoresis lanes obtained by PCR-DGGE were legible and distinguishable.The profiles of PCR-DGGE indicated that heavy metals accumulat ion at different levels markedly caused damage to farmland soils DNA, affecting the soil microbial richness and structure of dominating bacterial populations in the farmland ecological systems, and changing the structural diversity of microbial community.The FastPrep ®system is also suitable for rapid efficient extraction and purification of soil total community DNA from farmland soils polluted with mixed heavy metals and in turn the DNA can be used directly for PCR-DGGE analysis.