NOVELTY - Preparation of buffer layer involves adding zinc sulfide and zinc oxide to form powder material, adding zirconia balls, pure water and dispersant, mixing, milling, then pouring obtained slurry into a porous mold, drying, sintering, forming high-density sputtering target material, cutting and polishing surface of target material, measuring target density, placing glass as substrate in magnetron sputtering machine, evacuating, forming molybdenum film by sputtering, forming copper-indium-gallium-selenide absorber layer, and sputtering.    USE - Preparation of buffer layer used for copper indium gallium selenide solar cell.    ADVANTAGE - The buffer layer having excellent quality and durability is prepared, provides copper indium gallium selenide solar cell having improved conversion efficiency.    DETAILED DESCRIPTION - Preparation of buffer layer involves adding 10.0-45 wt.% zinc sulfide to powder material, adding zirconia balls, pure water and dispersant, mixing, milling for 4-24 hours, then pouring obtained slurry into a porous mold, drying for 12-36 hours, adding multiple oxide and sulfide, sintering at 800-1200 degrees C for 3-24 hours, forming high-density sputtering target material, cutting and polishing the surface of target material, measuring target density by Archimedes method, placing glass as substrate in a magnetron sputtering machine, evacuating the sputter chamber at pressure of (0.7-0.9)x 10-5 torr with argon gas as working gas by vacuum pumping system, purging argon gas into sputtering cavity component at pressure of (2-5)x 10-3 torr, forming molybdenum film with thickness of 500-800 nm by sputtering, forming copper-indium-gallium-selenide absorber layer having thickness of 1500-2000 nm, then plating thin film, evacuating sputter chamber at pressure of (0.7-0.9)x 10-5 torr by vacuum pumping system, purging argon gas at pressure of (2-5)x 10-3 torr, sputtering by radio frequency power. The film thickness of transparent buffer layer is 80-150 nm. The mass ratio of powder material, zirconia balls, pure water and dispersant is 0.8-1.2:2.5-3.5:0.2-0.3:0.005.