The invention discloses environment-friendly lightweight concrete and a preparation method thereof. The environment-friendly lightweight concrete is prepared from 300 to 450 parts by weight of cement,50 to 120 parts by weight of fly ash, 100 to 300 parts by weight of slag, 50 to 150 parts by weight of a foaming ceramic, 5 to 7 parts by weight of polyphenylene granules, 160 to 200 parts by weightof water, 9 to 13 parts of additives and 0.3 to 0.4 parts by weight of a thickener. The preparation method comprises crushing the foaming ceramic according to the above weight ratio, screening the powder by a sieve of 200-300 meshes to obtain ceramic powder, orderly adding cement, fly ash, slag, the ceramic powder and polyphenylene granules into a mixer, carrying out uniform mixing, adding 75% ofthe weighed water into the mixture, carrying out stirring for 1-5min, adding rest 25% of water, additives and a thickener into the mixer, and carrying out stirring for 1-5min to obtain a product. Theenvironment-friendly lightweight concrete has the advantages of high utilization rate of waste resources, high strength and long service life.