Simultaneous multi-threading (SMT) technology is the standard of modern high-performance processor technology, which is important micro structure optimization technology to improve the thread level parallelism. Compared with cross-cores and cross-processors, the timing channel security in SMT technology is more difficult to deal with and protect, and new security problems have emerged successively. At present, there is no systematic method to describe the timing channel security problem in SMT environment. Starting from the principle of timing channel attack using SMT technology, focusing on the timing channel attack generated by shared resources in SMT environment and its attack mechanism, based on the topological sort graph (TSG) model and data flow analysis extension, a description model of timing channel security problem suitable for SMT environment, ETSG-SMT is proposed. Firstly, this study introduces the technical characteristics of the utilization and protection of timing channel under SMT environment and the limitation and deficiency of TSG model to analyze these security problems. Then, on the basis of TSG model for SMT technical characteristics and its security problems of formal description characteristics combined with data flow analysis technology, a set of new modeling method is formulated. Finally, by applying ETSG-SMT model to the existing time channel attack methods and protection cases in the SMT environment, it is proved that the ETSG-SMT model has a sound application value in the analysis of the principle of timing channel attack and the derivation of protection technology in the SMT environment.