Abstract: Based on the test results of saline soil samples of twelve places(Kashi,Sinkiang,China),the representative crude saline soil samples were selected for the experiment of freezing and thawing cycles in laboratory.The salt expansion laws of crude saline soil were researched by use of three kinds of soil.It was shown that salt expansion value of low liquid-limit clay was accumulated before the sixth freezing and thawing cycles,but the increment of salt expansion was reduced gradually with increasing cycles;the salt expansion accumulation of low liquid-limit clay could be separated into three phases;the deformation of clayey sand was mostly frost heave and subsidence under cycles,and collapsibility value of clayey sand was accumulated with increasing cycles;the variation of salt expansion ratio and collapsibility ratio was a parabolic function of freezing and thawing cycles.