The road site construction of mountain wind farm is difficult,with steep transverse slope,poor physical and mechanical properties of soil surface,high backfill height of embankment slope,and frequent landslides in rainy season,resulting in road collapse.It will affect the construction progress,resulting in human,material and financial losses.Through combining with the engineering practice,the study analyzes the stability of high and steep backfill slope under rainfall conditions with FLAC 3D numerical software,and the influence rules of original terrain slope,backfill slope slope and compaction degree on its stability.The results show that rainfall has great influence on the stability of high and steep backfill slope of wind farm road.In the construction process,it is necessary to improve the measures of cutting drainage in time,adjust the slope ratio and slope height of the design backfill,so as to improve the stability of the embankment slope economically and effectively.In addition,the original terrain slope and backfill slope also have important effects on slope stability.