Constructing engineering structures on soft and loose soil because of large settlements, shear failures, and other geotechnical issues has many risks. Thus, one of the fundamental methods for having a stiff subgrade is soil reinforcement. Due major problems in environmental engineering, so to reduce environmental to the fact that factories' waste disposal is considered as one of today's fibers and steel slag fibers are two types of these new reinforcements, which pollution these wastes are used to improve soil engineering properties. PP regards the simultaneous impact of these reinforcements on the soil properties are currently being explored a lot in mixing different soils, including sand. As fibers separately and simultaneously with each other using direct shear test. The has not been considered, the main purpose of this study is to determine the strength parameters of reinforced sandy soil with PP fibers and steel slag fibers are in a length of 12 mm, which are added to soil in three different used steel slag fibers have 6, 12 and 18 mm length, which they are considered in three percentage 0.2%, 0.3%, and 0.4% of dry weight of soil. The applied PP ratios 0.5, 1 and 2 of steel slag fibers to PP fibers and tested. The results of direct shear test on samples of sandy soil reinforced with steel slag fibers indicated that adding these fibers to the soil would increase the shear strength, the soil cohesion and the angle of internal friction of the samples in comparison with the unreinforced condition. According to the results of the experiments, the optimum amount of steel slag fibers is 0.3% for combining with different proportions of the PP fibers. In addition, the results of the direct shear tests on the sandy soil mixed with the PP fibers showed that in this case, like the instances that the steel slag fibers were used, the soil cohesion parameter from the results of the diagrams obtained from the direct shear test that the is more affected by the amounts of PP fibers. It can be seen maximum increase of shear strength is related to the composition of the 0.3% of slag fibers to the PP fibers that causes the average increase of 55% at all the steel slag fibers with a length of 12 mm in the ratio of 0.5 of the steel normal stress levels in a mixture of sandy soil with the steel slag fibers and 0.9% of the PP fibers to the soil, and 0.9% of the steel slag fibers and PP the PP fibers by hybrid method in relative to unreinforced sandy soil. In addition, in states of the adding 0.9% of the steel slag fibers to the soil, slag fibers by hybrid method to the soil (0.3% of the steel slag fibers and which the advantage of using the hybrid method in reinforcing of the sandy ratio of 0.5 of steel slag fibers to PP fibers), respectively, the increase in shear strength at the 80 kPa of normal stress level is equal to 33%, 17% and 52%, soils can be concluded. On the other hand, by performing a triaxial compression test on the sandy soil and optimum mixture obtained from the direct shear test (0.3% of the steel slag of the sandy soil and hybrid mixture were obtained 31 and 40 degrees, respectively, fibers and ratio of 0.5 of steel slag fibers to PP fibers), the friction angle pressure of 100 kPa, it can be seen that the shear strength improvement of also cohesion were 0.9 and 6.6 kPa. By comparing the deviator stress acquired from the triaxial test on the sandy soil and the optimum mixture at a cell indicates the correctness of the achieved results. about 58% is obtained by using fibers with the hybrid method, which in comparison with the shear strength improvement in the direct shear test,