The invention provides a health-preserving health food formula beneficial for improving sleep and a preparation method thereof. The health-preserving health food formula comprises the following raw materials in parts by weight: 600-1400 parts of medlar, 600-1500 parts of rhizoma polygonati, 600-1500 parts of poria cocos, 1000-2000 parts of rhizoma dioscoreae, 800-1300 parts of mulberry, 500-1300 parts of radix polygonati officinalis, 800-2000 parts of lotus seeds, 800-2000 parts of arillus longan, 800-1400 parts of lilium brownii, and 800-1700 parts of spina date seed. The preparation process adopts a traditional water decoction extraction method, an extract is directly sub-packed into bags, the process is simple, and taking is convenient. The health-preserving health food formula is capable of improving the sleep quality, stabilizing emotion, relieving depression, stress and anxiety, enhancing immunity, memory, logical thinking ability and comprehensive ability, and improving the work efficiency.