Was the sharp decline in international trade between 2008 and 2009 the result of the financial crisis, or was the trade system inherently unbalanced before the crisis? The answer to this question helps us to comprehensively understand the causes of the financial crisis, and warning signals of the financial crisis hidden in the trading system. By using the methods like trade network analysis, this paper detects the early warning role of trade web evolution in the financial crisis and the causes resulting in the early warning role, thereby revealing the deep relationship between trade web evolution and the financial crisis. It comes to the following results:firstly, changes in trade network structure actually foreshadow early signals of the financial crisis, and these changes are also an important factor affecting the crisis; secondly, the warning role of trade web evolution in the financial crisis is related with the unbalanced trade gains, and continuous accumulation of imbalance risk eventually leads to the financial crisis; thirdly, the financial crisis cycle has corresponding relationship with the trade imbalance between important trade bodies, and the trade bodies with the gain disadvantages are more vulnerable to the financial crisis. The results show the changes in the trade network structure can become the new tool for early warning of the financial crisis. At the same time, regulators can predict international trade development trend and optimize trade policy preferably by exploring the trade imbalance reflected in the changes in the trade network structure.