We used the seed-voxel method to construct a brain function network and divided the community structure by greedy algorithm based on the n-back task. And then, we explored brain function network community structure robustness based on improved perturbation model. The results showed that random disturbance has little effect on the community structure, brain function network showed strong robustness. However, the brain function network showed vulnerability in the case of deliberate disturbance. Finally, we found that community connection strength was negatively correlated with robustness, community structure in the best divided state not mean the community robustness reach best, and no synchronization between them.