The psychological account is the process of the individual's psychological coding, classification and evaluation of economic behavior. The mechanism of calculating the mental account has its specific rules of economics. On the basis of the existing psychological account theory, this paper uses the event-related potential (ERP) method to study the neural mechanism of the mental account calculation mechanism after the full verification of the mental account mechanism, and draws the conclusion for the theory of computing mechanism in the mental account provides cognitive neurological evidence. The results show that at the level of response, the main effect is not significant, but the commodity category × commodity balance interaction significantly[F(1,12)=7.042,p=0.021<0.05]; at the correct rate level, the main effect is not significant, but the commodity category × commodity balance interaction significantly[F(1,12)=14.897,p=0.002<0.05]. Individuals in the psychological account operation to activate the refrontal brain area, the difference is more sensitive to small commodities. Whether it is the difference between the different goods or the different types of goods will have an impact on the individual mental accounts of cognitive processing.