本文给出了一个经过拓展的财政支出乘数模型。该模型表明 ,财政支出乘数是边际消费倾向和边际投资倾向两种因素的函数 ,且同这两种因素成正相关关系。利用上述模型进行分析 ,中国财政政策效应有限 ,根源于体制因素和结构因素 ,使得边际消费倾向和边际投资倾向较小 ,从而导致财政支出乘数较小。为此 ,须从制度安排和结构调整的角度入手 ,来提高边际消费倾向和边际投资倾向 This article gives an expanded model of fiscal expenditure multiplier. The model shows that the fiscal expenditure multiplier is a function of both marginal propensity to consume and marginal propensity to invest, and is positively related to these two factors. Using the above model for analysis, the limited effect of China’s fiscal policy stems from institutional and structural factors, making marginal propensity to consume and marginal investment less likely, resulting in a smaller fiscal multiplier. To this end, we must start from the institutional arrangements and structural adjustment point of view, to improve marginal propensity to consume and marginal investment trends