Conventionally, Instruction-Set Simulators (ISS) are widely adopted to run specific OSs for software simulation, but the achievable simulation speed is only few Million Instructions Per Second (MIPS). Operating System (OS) models are widely used to alleviate the overwhelmed complexity of running system-level simulation of software applications on specific OS implementation. Nevertheless, current OS modeling approaches are unable to maintain both simulation speed and accuracy when dealing with preemptive scheduling. This paper proposes a Data-dependency-Oriented Modeling (DOM) approach. By guaranteeing the order of shared variable accesses, accurate simulation results are obtained.