Abstract: Through the cyclic triaxial CD tests of compacted silts under controlled matric suction by using an unsaturated GDS triaxial apparatus,the deformation property analysis was made on the silts under cyclic loading,and the influence of matric suction,net cell pressure and dynamic stress amplitude were taken into consideration.Some conclusions can be made from the research as flowing.(1) Increasing of matric suction advances the soils' capacity of forresisting dynamic deformation under the same net cell pressure and dynamic stress amplitude.(2) Under the same net cell pressure and matric suctions,elastic deformation was observed at small dynamic stress amplitude which reached a stable state at final,but at large dynamic stress amplitude sample was damaged after a certain number of cyclic loading.(3)The influence of net cell pressure on the deformation property of unsaturated compacted silts was significant,small elastic deformation was exhibited at the larger net cell pressure,but plastic deformation was shown at the lower net cell pressure.