As various issues and impacting factors involved in the safety risk of complex systems, systematic and operational approach was desirable to instruct the evaluation process of safety risk for complex systems. Among the safety risks of a system, failure safety risk, the risk of accidents caused by various failures, is the most common system safety problem, so the evaluation of failure safety risk for complex systems was studied. The evaluation requires the support of explicit parameters and proper approach. Therefore, the paper presented the evaluation process of failure safety risk for complex systems, hierarchical evaluation parameters and approach, and examples were applied to demonstrate the evaluation process in detail. Results show that the proposed evaluation approach provides a feasible solution to evaluate the failure safety risk of complex system.