Abstract: Based on the soil test results of silty clay at different sites and depths in the plain area of Liaoyang City, Liaoning Province, the variability and correlation of 16 physical and mechanical indexes of silty clay are analyzed by unitary linear regression analysis. The results show that the soil types at different depths and locations are dominated by silty clay, with high water content, mostly in wet and plastic state. The variation coefficients of 7 physical indexes of silty clay including wet density, natural gravity, specific gravity of soil particles, saturation, porosity, liquid limit and plastic limit are small, while the variation coefficients of 4 mechanical indexes such as compression coefficient, compression modulus, cohesion and internal friction angle are large. There is a good linear relation between wet density and natural weight-specific density, and between liquid limit and plastic index of silty clay.