To examine whether abacus training improves working memory (WM), sixty-four children were randomly assigned into two groups, matched for intelligence. One group received abacus training for five years while the other group had no any abacus experience. WM was measured by a n-back task. The results showed that children with training were more accurate and faster than their peers. They also had greater activation and functional connectivity in the frontoparietal regions. The findings suggest that AMC training may be an effective method to improve WM in school children, which may have implications to help individuals with cognitive deficits.