Abstract: By the defensin gene, specific primers and probes of maca and rappini were designed, and the real-time fluorescence PCR methods for detection of both botanical components were established. The specificity of both methods were verified by using 33 samples DNA, including maca, rappini, and so on. Sensitivity test results showed that the absolute sensitivity for detecting both components reached 0.01 ng/L, the relative sensitivity was 0.1% (w/w), and the methods could accurately identify maca and rappini components in commercial maca products. Above all, the established methods could be used for the specific identification of maca and its adulterated component rappini in maca raw materials and its products.