Abstract: Through expansion mitochondrial of DNA fragments, a rapid PCR detection to identity the pork adulteration in fresh beef and beef piece was established.The amplification of mitrochondrial DNA was performed by using pre-denaturation at 94℃for 4min followed 30 cycles of holding at 94℃ (30s) , annealing at 59.4℃ (30s) and extension at 72℃ (30s) , with a 7min extension at 72℃after the last cycles.The amplified products were tested by the electrophoresis.By several rounds of experiments, the results of identification suggested it had high species specificity, stability, high sensitivity and it also provided a reference for the supervision department.This method was simple and rapid without double digests, which was suitable for a large sample.