To develop a real-time PCR based on TaqMan technology using the new MGB probe for detecting Chlamydia trachomatis DNA，plasmid containing the sequence of interest was constructed for the standardization of the method and to assess its sensitivity. Primers and MGB probe were chosen in the conserved region of cryptic plasmid pLGV440. The Results showed that this Chlamydia trachomatis assay had a threshold sensitivity of one genome copy number per reaction. A linear standard curve was obtained between 10⁰ and 10⁹ DNA copies/reaction (r＞0.990). Fifty clinical specimens were tested by real-time PCR and LCR simultaneously and the coherence was 100%. These observations suggested that real-time PCR based on MGB probe was an excellent candidate for a standard Chlamydia trachomatis detection method in a large scale.