[Objective] The effects of plant root system on freeze-thaw damage in seasonal-frozen highway slope were explored, in order to provide basis for plant selection of slope protection project.[Methods] The characteristics of soil and plant roots on highway slope in seasonal freezing area were investigated, effects of plant on freeze-thaw cycle were discussed by comparative analysis.[Results] The resistances of three plants to freeze-thaw damage were showed as follows:Robinia pseudoacacia > Lespedeza bicolor > Amorpha fruticose. Plant roots affected the process of freeze-thaw destruction by regulating soil physical properties and constituting soil-root structure. The existence of roots regulated soil moisture content and thus reduced the probability of soil settlement or crack.[Conclusion] Plants with deeper vertical root and wider root distribution were recommended to prevent freeze-thaw damage on highway slope in seasonal frozen area.