【Background】Herbicide-tolerant GM crops as a class of transgenic plants produce the global largest acreage of transgenic crops. For testing and monitoring of GMO safety, it is therefore important to develop methods for testing herbicide tolerant genes. 【Method】Using the tolerent of herbicide resistance gene aad1 anddmo nucleotide，PCR primers were designed, and PCR reaction systems were optimized. The specificity, sensitivity, reproducibility tests of the methods were carried out. Hence the detection methods of aad1 and dmo gene specific PCR were established respectively. 【Result】The PCR detection method was able to get stable and consistent results within the annealing temperature range of 56~64 ℃. The method could specifically identify crops containing aad1 ordmo gene among different kinds of transgenic crops with the detection sensitivity up to 20 copies or 40 copies. By mixing the detection primers of aad1 and dmo into the same PCR tube, a duplex PCR detection syatem was developed which would simultaneously amplify the two target genes in a single PCR system and with the same sensitivity as a single PCR. 【Conclusion and significance】The molecular methods developed in this study could accurately detect the genetically modified crops containing aad1 and dmo gene, with good specificity and high sensitivity. This method could provide a reliable technical support for screening and testing the herbicide-tolerant GM crops.