For rapid evaluation of slope stability, 44 typical slopes along Tangtun highway were investigated. The factor analysis method was adopted to analyze 7 evaluation indicators of slope stability, i.e., slope gradient, slope height, lithology, slope structure, structural plane cementation, main discontinuity and rock mass integrity. These indexes were sorted in light of their effects on slope stability, and evaluation indexes' grades after normalization were taken as evaluation indexes' weights. The research shows that from their importance, main factors are listed as slope shape, slope structure and structural plane characteristics in proper order, and sorting of evaluation indexes is in turn rock mass integrity, lithology, slope structure, main discontinuity, structural plane cementation, slope gradient and slope height.