Surface modification of basalt fibers was carried out using potassium oleate solution, the effects of different concentrations of potassium oleate solution on the surface treatment of basalt fibers and the comprehensive properties of natural rubber (NR)/basalt fiber (BF) composites influenced by basalt fiber orientation were investigated. The results show that with the increasing oleic acid concentration, the tensile strength, tear strength, and elongation at break of the composites initially increase and then decrease, reaching the maximum values at a potassium oleate concentration of 7%. The tensile strength and tear strength are increased by 15.6% and 12.1%, respectively. After being oriented, the BF reduces the Payne effect of the composites. The composites prepared with radial orientation show a 2.3% increase in tensile strength, a 17.8% decrease in elongation at break, and an 8.3% increase in wear. Scanning electron microscopy (SEM) analysis reveal that 7% concentration of potassium oleate can be uniformly coated on the surface of BF, resulting in better dispersion of the fibers in the rubber.