The invention discloses an environment-friendly medical instrument cabinet capable of automatically adjusting the luminance. The environment-friendly medical instrument cabinet comprises a box body, several cavities are formed in the box body, a placement device is arranged in each cavity and comprises a framework, several first idler wheels are arranged under the frameworks, inclined plates are arranged under the first idler wheels, support pillars are arranged under the inclined plates, and connecting shelves are fixedly arranged at one sides of the frameworks; second idler wheels are arranged on the connecting shelves, connecting plates are fixedly arranged in the frameworks, conductor elastic sheets are arranged on the connecting plates, several placement plates are arranged at the portion, located on the frameworks, at one sides of the connecting plates, several clapboards are fixedly arranged on the placement plates, baffles are arranged at the two ends of each clapboard and fixed to the frameworks, placement box bodies are arranged between the clapboards, and several LED lamps are arranged on the clapboards. The environment-friendly medical instrument cabinet has the advantages that convenience is brought for relevant personnel to seek for instruments, the time for seeking for the instruments is greatly shortened, and the precious time for treating and curing patients isprolonged.