Two pretreatment methods of grinding and boiling and two extraction methods such as the improved CTAB method and the kit method are combined respectively to compare the effect of extracting bacterial genomic DNA from the mouse feces.The results show that the concentration and purity of the genomic DNA extracted from the milled pretreated samples are higher than those obtained by the boiling pretreated samples,the integrity of the DNA extracted by the grinding combined with the modified CTAB method is better...