非银行金融机构是指以发行股票和债券、接受信用委托、提供保险等形式筹集资金，并将所筹资金运用于长期性投资的金融机构。

通常翻译为 non-bank financial intermediaries或non-bank financial institutions或non-banking financial institution。

世界银行对其的定义为：A nonbank financial institution (NBFI) is a financial institution that does not have a full banking license and cannot accept deposits from the public. However, NBFIs do facilitate alternative financial services, such as investment (both collective and individual), risk pooling, financial consulting, brokering, money transmission, and check cashing. NBFIs are a source of consumer credit (along with licensed banks). Examples of nonbank financial institutions include insurance firms, venture capitalists, currency exchanges, some microloan organizations, and pawn shops. These non-bank financial institutions provide services that are not necessarily suited to banks, serve as competition to banks, and specialize in sectors or groups.

其主要作用有：NBFIs supplement banks in providing financial services to individuals and firms. They can provide competition for banks in the provision of these services. While banks may offer a set of financial services as a package deal, NBFIs unbundle these services, tailoring their services to particular groups. Additionally, individual NBFIs may specialize in a particular sector, gaining an informational advantage. By this unbundling, targeting, and specializing, NBFIs promote competition within the financial services industry.

Having a multi-faceted financial system, which includes non-bank financial institutions, can protect economies from financial shocks and recover from those shocks. NBFIs provide multiple alternatives to transform an economy's savings into capital investment, which act as backup facilities should the primary form of intermediation fail.

However, in countries that lack effective regulations, non-bank financial institutions can exacerbate the fragility of the financial system. While not all NBFIs are lightly regulated, the NBFIs that comprise the shadow banking system are. In the runup to the recent global financial crisis, institutions such as hedge funds and structured investment vehicles, were largely overlooked by regulators, who focused NBFI supervision on pension funds and insurance companies. If a large share of the financial system is in NBFIs that operate largely unsupervised by government regulators and anybody else, it can put the stability of the entire system at risk. Weaknesses in NBFI regulation can fuel a credit bubble and asset overpricing, followed by asset price collapse and loan defaults.

英文来源：https://www.worldbank.org/en/publication/gfdr/gfdr-2016/background/nonbank-financial-institution