This article puts forward and analyzes the main reasons and influencing factors of soil-cutting's collapse in frigid zone,especially expounds the concept,cause,distribution characteristic of "waterline" and its influence on side slope stability.The mechanical model of cutting side slope stability in frigid zone is put forward according to the research above.Through checking computation of stability of soil-cutting side slope with saturated soil in melting period in different grades(1∶1,1∶1.5,1∶1.75),the authors bring forward effective measures adopting drainage to stabilize side slope instead of cutting it in frigid zone,namely,the comprehensive stability technology of side slope by digging dendritic infiltration ditch and laying geotextile as underlayer drainage in side slope,and(adopting) net geotextile lattice to stabilize soil and planting Malian grass whose roots are active and developed in it.The technology had been applied for some sliding collapse sections of Habin-Tongjiang Highway.After enduring two cycles of freezing and thawing,the ideal preventive and improving effect of this technology is proved.