Abstract: This paper, based on statistical analyses of the observed data, dealt with the spatial probabilistic characteristics of shear strength indexes for silty clay in Taiyuan. The statistical data were obtained on the basis of the engineering geologic investigation reports and strength tests in lab .The spatial variability coefficients of the indexes for Taiyuan silty clay were compiled.And also the Beta distribution for strength indexes of Taiyuan silty clay was established. Finally the paper studied the correlation between indexes and got some empirical equations.Besides, the paper studied thoroughly the correlation between the strength indexes of different tests, and the uncertainty of strength test method.