Abstract: Arbitrary Primer PCR (AP-PCR) analysis was used to Study on the characteristics of molecular epidemiology for Salmonella typhi belonging to phage type M₁ isolated in Jiangsu Province. Methods 26 isolates of Salmonella typhi belonging to phage type M₁ isolated in Jiangsu Province during 1988-1997 were analyzed by AP-PCR. Results Three primers screened among eight primers were suitable for AP-PCR of these isolates. Primer 22732、22733 and 22734 revealed 2、3 and 3 gene types respectively. Seven gene types were revealed combined the results of the three primers. Conclusion More gene polymorphous were obtained in higher strength epidemic years of typhoid fever from the evening of 1980 to the incipient of 1990 than lower strength epidemic years in recent years in Jiangsu province.