The invention discloses lightweight thermal insulation concrete and a preparation method thereof, and belongs to the technical field of concrete. The lightweight thermal insulation concrete is prepared from, by mass, 33-71% of a cementing material, 7-37% of expanded perlite, 0-30% of sand, 6-38% of vitrified microbeads, 0-1.5% of bast fiber, 2-13% of ultrafine mineral powder and 19-27.4% of water.The invention further discloses a preparation method of the lightweight thermal insulation concrete. According to the lightweight thermal insulation concrete, perlite serves as coarse aggregate, vitrified microbeads and sand serve as fine aggregate, and by adding the natural bast fiber, the properties of crush resistance, tensile strength, bending resistance, shock resistance and the like of concrete are optimized; tests verify that the two thermal insulation materials of the vitrified microbeads and expanded perlite are matched with each other, the thermal insulation property of the lightweight thermal insulation concrete such as thermal insulation lightweight aggregate can be improved. By mixing a small quantity of sand, the strength can be improved on the premise that the concrete lightweight and thermal insulation properties are guaranteed, and the comprehensive performance is enhanced.