Proposed by Ministry of Education P.R.C, Advanced Computational Infrastructure (ACI) aims at sharing geographically distributed highperformance computing and huge-capacity data resource among the universities of China. With the fast development of large-scale applications in ACI, the security requirements become more urgent. After analyzing the background of ACI, the paper describes the special security needs in ACI, and then presents TH-SMS, a security management system based on ACI. According to its three level structure, the implantations of TH-SMS are discussed. Especially for task security management, several new security techniques KCKPT, DP-VPN are introduced in the paper. Finally, compared with other security systems TH-SMS proves to be more effective and flexible.