SimpleScalar is a superscalar processor monitor which is used widely in performance analysis. This paper first analyzes the internal architecture of SimpleScalar, and on this basis, in-depth analyzes the mechanism to achieve branch prediction. Through an in-depth study of Perceptron-based branch predictor imple- mentation mechanism, it proposes a design to let SimpleScalar support Perceptron-based branch predictor. And this has practical significance for superscalar processor performance modeling and research.