Based on the scaffolding safety technical standard, risk evaluation index system of overturning and falling accidents of scaffolding was established, 17 risk factors were determined, and a risk evaluation model based on set pair analysis method was established. weight and degree of risk. According to the principle of the Set Pair Analysis, the risk grade of each factor is divided into three levels. According to the expert's score and the weight coefficient of each risk factor, the same degree, difference degree and contrast degree are determined. Using special value method, this method is applied to the project example, and the result is that the risk level of overturned and falling accident of attached scaffolding is in controllable condition, which is in accordance with the engineering.