An important issue of real-time software development is to analyze and predict the execution time of real-time software. A kind of visual prediction and analysis framework of the execution time of real-time software based on program flowchart is proposed in the paper. The key issues of implementing the framework are discussed in detail, including creating the mapping between intermediate code segment and statement line of source code, retrieving the time of any given program segment from the perspective of CPU cycles of goal machine instruct, calculating CPU cycles of statement lines of source code, point-to-point WCET_C (worst case execution time calculated) analysis algorithm based on program flowchart, and transforming CPU cycle into physical time. Based on the framework, a practical tool has been developed to predicate and analyze visually the program execution time. Finally, conclusion and comparison between the work in this paper and others is given.