Take subgrade soil from Huangpu Road near Dalian Maritime University as research object, compression tests were carried out in different confining pressures and different times of freezingthawing cycles using SLB1 triaxial apparatus, and the effects of freezingthawing on subgrade soil were studied . Under the condition of combination of different confining pressures(0~800kPa) and different times of freezingthawing cycles (0~20), the change law of moisture content, principal stress differencestrain and strength parameter is obtained. Results show that under the same times of freezingthawing cycles，shear strength increases with increasing of confining pressure. Under the same confining pressure, internal frictional angle, cohesive strength and shear strength present the tendency of reducing first and then increasing with the increase of the times of freezingthawing cycles, however moisture content presents the tendency of increasing first then reducing with the increase of the times of freezingthawing cycles. The turning point is about in the position of 7 times. Over consolidation effect mechanism is used to analyze the characteristic change of frozenthaw process.