A preparing method of nano-silver containing medical chitosan thermosensitive hydrogel is disclosed. A product of the method is a novel medical material. The thermosensitive hydrogel has good bacteriostatic functions for Gram-negative bacteria represented by escherichia coli, Gram-positive bacteria represented by staphylococcus aureus and fungi represented by candida albicans, and is wide in bacteriostatic spectrum, free of cell toxicity, efficient and low in toxicity. After uniform spraying of the thermosensitive hydrogel, a gel film layer can be formed on the surface of a wound. The thermosensitive hydrogel is durable in bacteriostatic functions and good in gas permeability and hygroscopicity, has functions of promoting wound surface healing, arresting bleeding, arresting pain, reducing inflammation and sterilizing, can be used for burn, scald, trauma, and other large-area irregular wounds, is capable of rapidly arresting bleeding and pain, preventing infection and promoting wound healing, and can be used for bedsore, skin ulcer, tinea manus and pedis, woman colpitis, cervicitis, cervical erosion, and other skin inflammation diseases.