Abstract: This paper studied different water content and different fiber content and different degree of compaction of fiber reinforced loess cohesion,internal friction angle and shear strength variation by direct shear test.The results show that:the moisture content increased from 14%to 18%,the cohesion of loess decreases when it is greater than 20%,the cohesion decreases rapidly;when the moisture content is 18%,the maximum internal friction angle and the shear strength reaches the maximum value;fiber materials in the surface,mesh and clumped distribution in loess soil,cohesive strength and internal friction angle increases with increasing fiber content increased first and then decreased.The amount of fiber is 0.5%of the optimal amount of fiber;fiber content is less than the optimal amount of fiber,increase the small change of internal friction angle with the degree of compaction,when the fiber content is larger than the optimal amount of fiber,the internal friction angle changes greatly;at the same time,in the actual application in this experiment,the relationship between moisture content,fiber content and compaction degree,internal friction angle and cohesive force is given,which is of guiding significance to the construction of loess area.