Abstract: This paper studied the main factors which affected the detection of genetically modified components in deep maching rice noodle with real- time fluorescent PCR method, so as to improve the detection sensitivity and effect.Simulate rice noodle sample with different content of genetically modified components was made and major factors that mainly affect the test results were analyzed, including samples particle fineness, samples in CTAB buffer solution temperature bath time. Results showed that when the sample fineness was 100 mesh and CTAB buffer incubating time was 8h, the results of DNA extraction and PCR detection were the best. Under optimal combination of conditions, the sample GMO detection limit was 0.001% GM content, which was 10 times of usually fluorescent PCR detection limit which was 0.01%.