Attempting to improve reinforcement effect on basalt fiber/polylactic acid composites, this study evaluates the effects of silane treatment, atmospheric glow discharge plasma polymerization, desizing, and addition of maleic anhydride coupling agent. The treated fibers were characterized, in terms of surface morphology and existing molecular bonds, and the mechanical properties of the composites were tested (i.e. strength, stiffness, and elongation at yield). Among the fiber surface treatments and the addition of coupling agent, improved mechanical properties were only shown by the silane treated and the atmospheric plasma polymerized composites by having 26 and 22% higher strength, respectively, as compared with the untreated one.