Abstract: In this experimental study,the shape,particle size and concentration of the steel aggregate additive were op- timized to directly improve the strengthening effect of the anchorage system by increasing the shear resistance of the resin anchoring agent at the failure interface and changing the original direct shear failure mode of the anchoring a- gent. Furthermore,the study enhanced the degree of reinforcement of the steel ag-gregate to the anchoring force of the specimen. The test was conducted by adding steel grit with a particle size of 1. 5,2. 0,and 2. 8 mm and steel shot of 1.4,2． 0,and 2. 5 mm to the bulk slow resin anchoring agent,and each particle size was further divided into 30,40 and 50 kinds in total. A ϕ20 mm right-lateral rebar and steel sleeve with length of 100 mm,inner diameter of 30 mm and wall thickness of 7. 0 mm were used to make anchoring specimens. Then,an electro-hydraulic servo universal tes- ting machine with 2 mm / min of loading mode was used to collect data for the pullout test,and the effects of different steel aggregate additives on the average anchoring force were analyzed based on the theory of doweling effect. The test data showed that the average anchoring force of the anchoring specimens with the steel grit and steel shot is 125. 6 and 129. 0 kN,respectively,increasing by 6. 4% and 9. 4% ,comparing with the specimens without adding steel aggregate. Among them,the average anchoring force of specimens with particle sizes of 1. 4-1. 5,2. 0-2. 0 and 2. 5-2. 8 mm is 127. 6,124. 7 and 129. 6 kN,respectively,which increased by 8. 1% ,5. 7% and 9. 8% ,showing a trend of decreasing first and then increasing. While the increase in the amount of adding steel aggregates presents a gradual decrease in the degree of improvement of anchorage force,i. e. ,the average anchoring force of the specimens with the aggregate amount of 30,40,50 is 128. 5,127. 2 and 126. 2 kN, respectively, with an increase of about 8. 9% ,7. 8% and 6． 9% . In this experiment,the maximum anchorage force is increased by 14. 5% ,with an average anchorage force of 135. 1 kN,from steel shot with an added quantity of 30 and a particle size of 1. 4 mm. The failure mode of the ancho- ring agent in the test is shear failure,and the doweling effect produced by steel aggregate causes scratches on the fail- ure surface of the anchoring agent. According to the analysis of the failure mechanism of the anchorage section,the im- portant effects of shear strength and residual shear strength parameters of the anchoring agent on the anchoring effect are further discussed.