Hybrid network emulation has emerged as a new way to exploit advantages of both network simulation and emulation. Hybrid network emulation often uses a technology called time dilation to combat performance limitation. In order to implement accurate time dilation, we define the concept of Emulation Fidelity. We calculate the time dilation factor by evaluating Emulation Fidelity. Fidelity evaluation based time dilation improves correctness of large-scale high-throughput network emulation with maximum efficiency.