The invention relates to an environmentally-friendly carpet tile backing material and a preparation method thereof. The environmentally-friendly carpet tile backing material comprises the following components: 14-22 wt% of ethylene-propylene-diene monomer (EPDM), 34-58 wt% of high-pressure low density polyethylene (LDPE) and 14-22 wt% of atactic polypropylene APP,which are served as a matrix material, and 14-22 wt% of CaCO3 served as a filler. The preparation method comprises mixing, fusing and shaping. Raw materials adopted by the invention are environmentally-friendly materials and do not pollute service environment and users; the prepared backing material has favorable mechanical property which exceeds the national standard; the preparation method is simple and suitable for industrial mass production.