Shadow banking system is a dynamic and complex three-dimensional institution combining products，institutions and markets. It broadly refers to the credit intermediation involving entities and activities outside the regular banking system. Its most basic function is the maturity transformation，liquidity transformation and credit risk transformation. There are three research frameworks of shadow banking in domestic study，which are based on “shadow banking regulation”，“shadow banking risk” and “non-traditional credit” respectively. Based on the non-traditional credit perspective，this study estimates that the scale of broad shadow banking system in China is about 27 trillion yuan，accounting for about 19% of the total assets of the banking industry. However，the scale of shadow banking system is just one aspect of financial system risk in China. More importantly，the non-traditional credit expansion mechanism of the banking system itself （shadow banking business） is a critical factor of the risk accumulation in financial system. Although the development of the shadow banking system is reasonable and innovative，it also highlights the drawbacks of the financial system in China. At present，the supervision of the shadow banking system is overall effective，but the relevance，completeness and predictability of the regulatory policy are still to be improved. We should continue to encourage and regulate the shadow banking system，prevent the regional and systemic financial risk，and deepen the reform of the financial system in China.