There are many direct reasons for the stock market crash, but at least one of the following conditions should be met: 1, a country's macroeconomic fundamentals have deteriorated seriously, and listed companies have difficulties in operating; 2. Low-cost direct financing leads to "inefficient" financial and "inefficient" economic development, which greatly leads to a bubble and the stock price is seriously overvalued. 3. There are serious defects in the listing and trading system of the stock market itself, which leads to the prevalence of speculation and the loss of investment value and resource allocation function of the stock market. 4, political, military, natural disasters and other crises have seriously hit the confidence of the securities market, and the securities market has psychological panic and cannot continue to operate normally.