Abstract: Early warning is the foundation of remove- warning and the traditional warning is based on the forecast. This paper presented a new warning method: way-decision tree warning. In view of the reality of China soybean production, this paper used the relative theory of early warning. Firstly, it set up a oybean early warning index system by analysis of China soybean market in the past eighteen years. Secondly, it extracted some regularity sets according to the warning sign index’s effects on the warning alert index by decision tree. Lastly, it established the early warning system of soybean import ependence degree. The conclusion shows that China soybean import dependence degree has remained in a serious warning state since 2002.