The approach of aggregating components into complex software systems is maturing with the rapid development of component technology. How to analyze software reliability from system architecture and components’ reliabilities should be answered. Software is static, while development process is dynamic. To enable reliability tracing through a dynamic process, this paper presents a general model for component-based software reliability-component probability transition diagram-based on function abstractions. Different from other related work emphasizing on mathematical modeling, the model presented here focuses on reliability tracing through the dynamic development process.