Natural disasters and cyber intrusions threaten the normal operation of the critical electric grid infrastructure. There is still no widely accepted methodology to quantify the resilience in power systems. In this work, power system resiliency refers to the ability of the system to keep provide energy to the critical load even with adverse events. A significant amount of work has been done to quantify the resilience for distribution systems. Even though critical loads are located in distribution system, transmission system play a critical role in supplying energy to distribution feeder in addition to the Distributed Energy Resources (DERs). This work focuses on developing a framework to quantify the resiliency of cyber-physical transmission systems. Quantifying the resiliency of the transmission network, is important to determine and devise suitable control mechanisms to minimize the effects of undesirable events in the power grid. The proposed metric is based on both system infrastructure and with changing operating conditions. A graphical analysis along with measure of critical parameters of the network is performed to quantify the redundancy and vulnerabilities in the physical network of the system. A similar approach is used to quantify the cyber-resiliency. The results indicate the capability of the proposed framework to quantify cyber-physical resilience of the transmission systems.