Abstract: This paper presents the symbolic trace testing methodology, gives the definition and generating methods of symbolic trace for C programs, and describes detailedly the C software testing tool STTT. STTT is designed to support the symbolic frace testing methodology and branch coverage analysis. It can provide users with seven tables about the dynamic execution behavior of the tested program. STTT has been implemented by Dual-68000 Computer and Greatwall-0520 Computer in Wuhan University.