In previous studies, an herb-resistant plasmid was extracted by alkaline lysis from Escherichia coli (E. coli) CP9 from urine of a patient with urinary tract infection (UTI). Results of trans-conjugation test showed that the herb-resistant gene was in the plasmid. Aim to determine the properties of the herbal resistance plasmid in E. coli CP9. Expression and immunological activity of target proteins were tested by Western blot, while expression of tra gene in the herb-resistant plasmid was detected by PCR. According to Western blot, bright fluorescence bands (33kDa and 44kDa specific protein band) were observed in the E. coli CP9, but not in the control group. The TrfA-33 protein (33kDa) and the TrfA-44 protein (44kDa) encoded by trf-A gene were expressed successfully in E. coli CP9. The results of PCR showed that there were 8 clear bands involving the herbal resistance plasmid DNA, while no amplification band was found in the control group. The amplified products were orf1 (406bp), orf2 (1035bp), orf4 (433bp), orf5 (359bp), orf6 (322bp), orf7 (326bp), orf8 (932bp) and orf10 (690bp). Tra gene was expressed in the herb-resistant plasmid. The herb-resistant plasmid contains an essential nucleotide sequences for DNA replication, namely, a replication origin. Moreover tra gene had a control over bacterial conjugation and transformation. All evidences support a sound conclusion that the herb-resistant plasmid belongs to conjugative plasmids.