Currently, most designs are usually based on the results of laboratory experiments to calculate the deformation of the soil. Therefore, the calculated results have much trouble accuracy. The authors carried out a field test in a number of works in Thai Nguyen, the authors use a static compression test method for determining the deformation field module. The research results have established the relationship between soil deformation modulus trom laboratory experiments and field test. Clay, hard plastic state, with e = 0.85 - 3.8 - kE = 3 - 3,8. Clay, semi-hard state, with e = 0,75 - kE = 2,7.- 4,5.