Abstract：In the reliability analysis of foundations，one of the most important problems is how to choose the reasonable statistical method for shear strength indexes of soils. According to the basic assumption of some topics in the soil mechanics，the indexes of shear strength are the parameters describing the trend of average strength of homogenous soils. The mean values and variance of local spatial averaging of soil properties should be used in the reliability analysis. So it is necessary to introduce the random field theory into the statistics for shear strength indexes and to consider the auto-correlation and cross-correlation of the shear strength indexes of soils. The stochastic statistical methods for shear strength indexes are presented based on the traditional statistical methods. Both the auto-correlation of the individual index and the cross-correlation between the indexes can be considered when using the methods. In addition，there is no need to study the auto-correlation function and cross-correlation function of and respectively. The variance of spatial averaging of and can be obtained directly through regression. The process of calculation will be simplified by this means. Finally，by calculating an example of engineering in Tianjin Port，it is proven that the reliability indexes calculated by the stochastic statistical methods agree well with the reliability of practical engineering.
