The invention discloses modified basalt fiber reinforced scoria lightweight aggregate concrete and further provides a preparation method thereof. The basalt fiber surface is processed to generate changes in an interface structure and chemical components of fiber, so that chemical activity of the basalt fiber surface is improved, the basalt fiber surface can form a tightly-bonded interface structure with a cement base body, excellent mechanical property of the basalt fiber is given to play, and further performance of the basalt fiber reinforced scoria lightweight aggregate concrete is improved. Smoothness and chemical inertness of the basalt fiber surface are effectively improved, so that the problem that the basalt fiber and a cement base material are difficult to bond is solved. Meanwhile, the ingredients of the modified basalt fiber reinforced scoria lightweight aggregate concrete are chosen from green and environment-friendly resources which are rich in source and low in cost; furthermore, the obtained novel modified basalt fiber reinforced scoria lightweight aggregate concrete has very excellent compressive strength, breaking strength and freezing resistance.