Abstract：This paper concludes the data of investigation，design，and construction for more than scores of landslides mitigation works in Wanzhou area of the second stage program of large geohazard control and prevention in Three Gorges Reservoir. Based on statistical analysis of shear strength parameters c and j in sliding zone along horizontal-stratum landslides in Wanzhou area and the fitting of probability density function from check method，it draws the conclusion that probability distribution form of cohesion c obeys the logarithm normal distribution，and angle of internal friction j，normal distribution. The probability density function as prior function is used to optimize a little sample of c and j of Guantangkou landslide in Wanzhou area through Bayes method，and the calculated results indicate that variance drops by 37.6% and coefficient of variation by 32%. In this way，the reliability of landslide control can be improved and optimization design will be realized.
