At first

based on the principle of least squares

the back-analysis method of the average shearing strength of the slip zone soils with multi-sections is discussed. Secondly

a back- analysis method of considering different slip segments with different shearing strength indexes is brought forward according to the difference of the matter components or whether eroded by groundwater in landslides. A practical example is introduced by using the two methods. Meanwhile

the landslide thrusts of a section calculated by utilizing the two kinds of shearing strength indexes are compared and analyzed. The results show that the calculation precision of the former is still comparatively reliable in landslide control and design when landslides are simple and in small scale. However the latter will be more reasonable and reliable in control and design of large or medium scale landslides as well as complicated ones.