Abstract: To make the brain neural mechanism of the addition and subtraction calculation clear and explore different strategies of the addition and subtraction calculations corresponding to the activating differences of the brain regions. An ACT - R model of meeting behavior experiment method was adopted to study the cognitive processing mechanism of the addition and subtraction calculations in finer time particles. The behavioral experiment results show that the the reaction time of the addition is (1812.14±224.14)ms and the subtraction is (2328.14±287.36)ms. And the accuracy of the addition is 97.92%±2.67%, while the subtraction is 74.38%±11.3%. The ACT - R model results show that when in ACT-R simulation, the addition is 1813.96ms, while the subtraction is 2314.53ms. And the fitting result between the model result and the real result of BOLD response in LPFC is 96%, while in PPC is 98%. Results show that the subtraction is much more complex than the addition.