The paper focuses on the acute problems of systemic financial risk in the economy of China posed by the real estate sector. In the event of collapse, the world's second-largest economy of this Asian giant, deeply integrated into the global system, can trigger spillover effects and a new global economic crisis. It is therefore important to deepen understanding of the internal mechanisms of systemic financial risk accumulation in the Chinese economy.  We research the microfinancial roots of systemic financial risk and macroeconomic mechanisms of its accumulation and materialisation after it has reached a critical level. Microfinancial roots of systemic risks are connected with excessive growth of financial leverage. We suggest a mathematical model of the optimal level of financial leverage and its safety threshold for the companies in the real sector including the construction and development sector. On the macro level, the paper presents a comprehensive dynamic scheme of non-linear relationships in the real estate industry, which unwind self-reinforcing cycles and lead to the accumulation of systemic financial risks. The main driving force of these processes is the institutional mechanism that we call collateral accelerator.  Under certain conditions, it plays the role of a powerful internal destabiliser of the economic system and provokes the unwinding of self-reinforcing cycles in the real estate market, the households’ finance, development companies, and the banking system.  The results of the research can help shape the optimal macroprudential regulatory measures to minimise systemic financial risks and ensure financial stability without suppressing economic growth.