The western flower thrip, Frankliniella occidentalis (Pargande), an invasive species worldwide, was first reported in Beijing in 2003 Morphological identification of thrips is difficult because of their small size, high degree of similarity, and polymorphism. In contrast, molecular identification is not hindered by phenotypic polymorphism, or the sex or stage of development of the target species. We evaluated the effectiveness of TaqMan realtime fluorescent quantitative PCR to identify WFT, for which we developed a pair of species specific primers and a MGB probe. The amplified fragment size was 138 bp. Standard points made using serial dilutions of plasmid DNA had a strong linear relationship with the detected Ct values (R² = 0.9965), making the C_t value a reliable way to quantify DNA. Specificity tests performed with the TaqMan-MGB probe and primer sets showed that all F. occidentalis specimens were detected and that there were no cross reactions with 8 other thrip species, including F. intonsa (Trybom) and F. tenuicornis (Uzel). Moreover, the system could quantitatively detect target DNA copies from all developmental stages of F. occidentalis with high repeatability and stability The results indicate that our detection system has high sensitivity and specificity and can be used for on-site testing of samples at portsofentry and during transportation of plant seedlings and products.