Through a systematical field investigegation of engeering geology on the south part of Masanfeng soil slope

using the method of limit equilibrium and FLAC

the stabiliy of this soil slope is analysed. The potential slip surface is founded

and the safety factor is calculated.The results indicated that the soil slope is unstable.By comparision the results of the two calculations

the failure mode and the developmental trend of the soil slope are analysed. The mechanical characteristics of this slope is the traction slope slide. The slope collapsed through various stages instead of one-time-collapse. The failure mode of the slope is a series of dynamic planar-circular slide.The failure will reached the back edge of the slope if the treatment isn’t done in time.