The secondary disasters of debris flow induced by Wenchuan earthquake,has been a top problem and one of important restrict factors of recovery and reconstruction after the earthquake,debris flow hazard assessment is a foundation and core technology of debris flow risk management.In this paper,31 debris-flow gullies along Dujiangyan-Wenchuan Highway(abbreviated to Du-Wen Highway) were taken as research objects.Based on the field investigation,remote sensing image interpretation,consult the corresponding literature data and other means to take basic data of debris flow gully in this study area,by choosing geology,topography,climate,hydrology factors and using the principal component analysis method to screen the key factors and grey correlation analysis method to determine the weighing values,established the debris risk assessment model,got risk value of every valley through the calculation.The assessment results show that:31 debris flow gully along Du-Wen highway are most at risk,among them extremely high level of risk occupies 23%,high risk 35%,moderate risk 13%,slightly dangerous accounted for 29%;and Hongchun gully,Xiaojia gully and Shaofang gully belong to the extremely high risk gully,Niujuan and Gaojia gully belong to high risk,so the full countermeasures must be taken in traffic line designing.