The shear strength of compacted loess is an important factor which seriously influencing the stabilization of the high loess-filled project. In order to study how the compaction degree and water content influence the shear strength,a series of direct shear tests with different initial compaction degrees and initial water contents are carried out for compacted Q₂ loess and Q₃ loess in Yan'an new district. Then,a preliminary discussion is conduct to find out the shear strength difference between compacted loess from backfill and samples prepared in laboratory. The results show that cohesion and internal friction angle increase with the increase of compaction degree, the clay content in compacted loess has a great influence on the cohesion and internal friction angle. Cohesion,internal friction angle and shear strength decrease with the increase of water content,and compacted Q₂ loess is more sensitive to water. The shear strength of compacted loess from backfill is much higher than samples prepared in laboratory.