Abstract: In order to improve the roadside safety of low-grade highways in mountain areas,a set pair analysis based on projection pursuit model is proposed.This method using the projection pursuit technology that can objectively deter-mine the index weighs of sample data from candidate roads,which avoids the subjectivity and limitation of experts.Tak-ing the features of evaluation indices into account,the definitive information coexists with dubious information.The set pair analysis theory is applied to establish an evaluation matrix on degrees of connection,which describes the relationship between evaluation indices and risk ranks from three aspects:identity,difference,and antagonism.In order to verify this model,the low-grade roads in the City of Chengde,China are selected as a case study .Compared to the method based on the grey cluster theory which considers data as value,this proposed model takes data as an information carrier,which contains more information and can make evaluation results more reliable.When evaluating the third segment in the case study,the evaluation result of gray clustering is [0.0332 0.1741 0.4171 0.3948],which shows its limitation when regard-ing samples as data,makes it difficult to determine the safety level between III and IV.By contrast,the evaluation result of proposed model is [0.1800 0.9701 2.382 0.2398],which clearly determine the safety level of the road as III.The results show that roadside safety assessment based on set pair analysis is more feasible and reasonable.