Abstract: Introducing investment decision equation to improve dynamic behaviour 19 proposed by authors^[1]. Based on the proposal, we discuss the necessity of further reform of Kaleski business cycle in order that the result of theoretical analysis coincides with the actual expanded reproduction process of capitalism. We also study the measures of improving dynamic behaviour of the model. In the analysis of discrete system with time delay, Z-transform is utilized, some numerical examples calculated, and the trouble caused by solving transcendental equation is avoided. As the order of characteristic equation becomes higher, the method proposed in this paper shows better its advantages. And microcomputers are found to be the suitable tools for researching dynamic problems. The wrong theoreticle solution of Kaleski model is found out and corrected in this paper.