Iron accumulation can induce a wide range of neuron disorders in central nerve system. Increased serum ferritin has been found to predict poor clinical outcome in ALS. We used quantitative susceptibility mapping to explore brain iron accumulation and theri clinical relevance. Increased iron level has been found in both cortical and subcortical motor related regions. The iron concentration in the primary motor cortex is responsible for deteriorated clinical syndrome, suggested its potential role for disease management. While increased iron concentration in the bilteral caudate contributed to impaired executive function, indicated network-based dysfunction for cognition decline in ALS.