Abacus-based mental calculation (AMC) training has the potential to induce cognitive plasticity. However, the neural correlates of such benefits remain unknown. In this study, we aimed to examine impacts of AMC training on task-related functional connectivity. We obtained functional imaging data from 23 children with AMC training and 21 control children. For AMC children, we found a increase in task-related functional connectivity within the frontoparietal regions, which was also significantly correlated with the speed in the 2-back condition. Therefore, AMC training may enhance the functional integration of frontoparietal circuity, and consequently result in improved task performance.