In order to overcome the disadvantages of existing complex network robustness research models in which only the local influences of disabled nodes and topological robustness are considered, the node load, utmost load and disabled model are defined by node efficiency and a new method to evaluate complex network functional robustness is proposed in which the whole influence of disabled nodes is considered. The complex network functional robustness is evaluated by the final disabled node proportion after beat and the optimized evaluation arithmetic is given. Experiments show that this method is effective and feasible in evaluation of complex network functional robustness in which the node load is considered, and it is applicable for large scale complex networks.