Abstract: The treatment of landslide hazard is a complex systems engineering. The selection of its treatment schemes is depended on many factors such as technology, economics, environment, and risk. Policymakers have preference information on alternatives, and the attribute weight information is incomplete. To cope with such decision-making question with incomplete and preference information, a similarity degree-based method for triangular fuzzy number multi-attribute with preference information on alternatives is proposed. By using this method, a linear programming model is established firstly, and the attribute weights are derived by solving this model, then, based on a possibility degree formula for comparing two triangular fuzzy numbers and a formula for priorities of complementary judgment matrix, a priority method for alternatives is presented. Finally, the method is applied to the decision-making of Zhafangping landslide in the Three Gorge reservoir area, and a good result is gained, which shows that the method is feasible and effective.