Minicore is a new microkernel based on Servant/Exe-Flow Model, in which the execution model and the storage model are independent of each other. The highly modularity design of microkernel made Minicore rely heavily on the inter-servant communication module, because a servant is the basic unit of the operating system. As a result, in order to analyse its time predictability, it is inevitable to conduct a time predictability analysis for Communication Modules in Servant/Exe-Flow Model. In the thesis, we estimate the WCET of Minicore's communication modules and analyze its time predictability with the definition of CIPr (Configuration-Induced Timing Predictability), providing data to support its future mechanism of timing predictability, and foundation for future work of time predictability analysis for Minicore. Static WCET analysis and a path-based algorithm have been adopted in our work. Applying to the communication modules in Minicore, the method includes four phrases:extract code snippets for each communication mode, analyse communication control flow, analyse processor features, and calculate WCET finally.