The C4 sub-genotype of Enterovirus 71(EV71) is identified as the most dominant sub-genotype circulating in Chinese mainland since 1998, while the circulation situation of EV71 before 1998 is not well established due to insufficient experimental data. The C1 sub-genotype of EV71 has not been reported in Chinese mainland by now. Based on AFP surveillance system of the mainland of China, this study performed a retrospective study of AFP cases for 1985-1999༚A strain of EV-A71 C1 sub-genotype was found. To our knowledge, this strain (SD92-41) is the first C1 sub-genotype reported in Chinese mainland. This study proves that the C1 gene subtype also appeared in Chinese mainland, but it is not clear whether it is an imported or a local epidemic strain. With sufficient information from retrospective studies, the source of the SD92-41 strain will be identified, and the prevalence of EV-A71 in Chinese mainland before 1998 will be clearer.