This paper studies the endogenous evolution of investment behaviour under the various macroeconomic circumstances, which might be relatively constructed by free-float, fixed and target zone regimes as the economic stability policy. It applies the issues of stock price target zone policy to a simultaneous stochastic differential equation system. We construct the stochastic macro model which utilized the basic conception of Dornbusch [1976] with the different price adjustment mechanism. In addition, we intend to apply the topological method which used by Miller and Weller [1991] to analyze the general economic property from the non-recursive model. The main purpose of this paper is to discuss how the public’s expectation affects the dynamic loci of commodity and stock price when the public agents have the perfect or imperfect credibility. We utilize this model to investigate whether stock price target zone regime will have honeymoon effect or not, when the government announce to execute the stock price target zone policy in the various situations. Moreover, we discuss whether stock price target zone can simultaneously stabilize other variables in the different situations.