With low system inertia, cyber-physical networked microgrids are sensitive to operation changes. A reachability analysis method is presented to efficiently quantify the impact of communication network latency on the dynamics and resilience of physical networked microgrids when secondary or tertiary control is used for operating DERs. Network latency is modeled by using zonotope technique and then integrates into reachable set calculation to efficiently evaluate the system subject to heterogeneous network latency. Extensive tests demonstrate the influence of latency on system dynamics as well as validating reachable set can provide an efficient estimation of system dynamics subject to latency changes. Numerical results also offer an insight into the enhancement of system's resilience through strategically designing and managing communication network.