在传统的宏观经济理论中,有一个重要的恒等式,即储蓄—投资恒等式。这个恒等式揭示了投资和储蓄之间的关系,即:经济投资规模由相关部门的储蓄额度大小决定,进行投资需要考量储蓄的规模,否则就不能实现供求均衡,从而影响经济的发展。储蓄—投资恒等式在分解经济部门的基础上,提出了经济投资规模由四个部门的储蓄额度决定的观点,即居民消费者、企业、政府和国外等四个部门的储蓄决定着经济投资规模。一般来说,如果储蓄是现 In traditional macroeconomic theory there is an important identity, the saving-investment identity. This identity reveals the relationship between investment and saving. That is, the size of economic investment is determined by the amount of savings in the relevant departments. To invest, the scale of savings needs to be considered. Otherwise, the balance between supply and demand can not be achieved and economic development will be affected. Based on the decomposition of the economic sector, the saving-investment identity puts forward the view that the size of the economic investment is determined by the savings quotas of the four departments. That is, the savings of the four departments, namely resident consumers, enterprises, government and foreign countries, determine the scale of economic investment. In general, if savings are now