The survivability of network is of vital importance with respect to the normal operation of information infrastructure. The current research works in the area of network survivability generally aimed at the definitions and quantifications of specific survivability attributes for distinct network objects. Unfortunately, there is a lack of research concerning how to model, measure and analyze the survivability of network in a consistent manner, and it is helpful to the unification of network survivability measurement and the promotion of related research works in the area of network survivability. Furthermore, the requirements for network survivability measurement are variable among different application domains. Therefore, a flexible mechanism to support the customizable measurement of network survivability is needed. In this paper, we propose a unified framework for network survivability measurement which is extensible and customizable. The customization method of network survivability measurement model and the process of network survivability measurement are analyzed in detail. The analysis result shows the generality and practicability of the framework.