[Objective] The influence of different gradients of wood fiber addition on the shear resistance of the waste soil at waste disposal site was analyzed， in order to provide data support for the improvement of the waste soil and the prevention and control of soil erosion at waste disposal site. [Methods] Taking the waste soil from the Xinpu village waste dump in the Chuxiong section of the Central Yunnan Water Diversion Project as the research object and using wood fiber as an additive， soil culture experiments were conducted by setting four gradient treatments of 0 （CK）， 1% （ML）， 3% （MM）， and 6% （MH） according to the mass ratio of wood fiber to waste soil. The cohesion and internal friction Angle of the improved waste soil under different gradients were obtained by the direct shear test. The influence of different gradients of wood fiber addition on the shear strength of waste soil at waste disposal site was systematically studied. [Results] ① The shear strength of the waste soil was significantly enhanced after the addition of wood fibers. Moreover， the improvement effect of the shear strength of the ML treatment compared with the control was the best under vertical stresses of 50， 100， 200 and 300 kPa， increasing by 51.22%， 64.93%， 71.25% and 70.35%， respectively. The greatest increase was under the vertical stress condition of 200 kPa. ② Adding wood fibers effectively enhanced the shear strength of waste soil. With the increase of the wood fiber gradient， both the cohesion and internal friction angle of the waste soil showed a changing trend of first increasing and then decreasing. Among them， under ML treatment， the cohesion and internal friction angle of the waste soil were both the largest， increasing by 53.56% and 77.11% respectively compared with the control. The cohesion of the waste soil under the MM and MH treatments increased by 48.67% and 11.41% respectively compared with the CK treatment. ③ Pearson correlation analysis indicated that the physical and chemical properties of the waste soil after the addition of wood fibers were closely related to the shear resistance performance. Through factor analysis， it was found that the addition of wood fibers mainly affects the shear strength parameters by influencing the soil bulk density， organic matter， field water holding capacity， saturated water holding capacity and capillary water holding capacity. [Conclusion] The addition of wood fibers enhances the shear strength characteristics of the waste soil in the waste dump. The addition of 1% wood fiber is most beneficial for enhancing the shear strength of waste soil. However， due to the differences between the actual engineering application and the soil culture test research， the applicable amount of wood fiber addition should be adopted simultaneously in combination with conditions such as vertical stress.