The invention discloses a light high-conductivity and heat-resistant aluminum conductor and a preparation method thereof. The aluminum conductor is composed of, by weight, 0.035-0.06% of B, 0.1-0.2% of Zr, 0.1-0.3% of Er, inevitable impurities and the balance Al. The technological process comprises the steps of smelting, on-the-spot fast component analyzing, refining, rapid cooling casting, blank annealing, extruding and drawing. The added B element has the refining and modifying effects and mainly has the effect of promoting supersaturated solid solutions containing Zr and Er to separate out Al3(Er and Zr) ternary composite phases; the Al3(Er and Zr) composite phases are nano particles which are coherent with a matrix and have shell-core structures, are dispersed in the aluminum matrix and can greatly improve the electricity conductivity and the heat resistance of the aluminum conductor; the density of obtained monofilaments is smaller than or equal to 2.71 g/cm<3>, the electricity conductivity of the monofilaments is greater than or equal to 62%IACS, the short-time heat-resistance temperature of the monofilaments reaches 230 DEG C, the long-term heat-resistance temperature of the monofilaments reaches 210 DEG C, and the tensile strength of the monofilaments is greater than or equal to 165 MPa; the economic benefits are remarkable, the energy is greatly saved, and the environmental friendliness is high.