With the increasing services supported by QKDN, and various requirements for the interoperation and coordination between QKDN and corresponding user networks, it is urgent to discuss QKDN robustness and carry out necessary standardization works. QKDN users expect continuously stable keys supply supported by QKDN, which brings strict requirements for robust QKDN operation. Network dependability assessment of QKDN is to evaluate the availability performance and its influencing factors, such as reliability, maintainability of network functions and components, quality of connections, so as to avoid destructive failures in QKDN. Besides, it can improve the level of effectiveness, precision and automation of the QKDN management in QKDN operation and maintenance. This Recommendation will carry out standardization study and specify QKDN dependability assessment conceptual model, indicators, and dependability assessment process.