Abstract: When the capital is transformed from the real type to the fictitious one ,the latter will be rapidly ditaled and the former will present a comparative diminution. Qualitatively the two forms are interaction ,The interaction would be benign and good to the economic development and it would also be a malignant cycle that may lead to an economic crisis; Whereas quantitatively there exist four quantitative relations between the real capital and fictions one: Spot mode , stagnancy mode , expansive mode and puffy mode .This article advocates that play to the activity of fictitious capital. it is important for us to give full in order to promote the economy . and monitor the interactive relationship between the real capital and the fictions capital.