The present invention relates to a clean constant-temperature constant-humidity system for an operating room. An objective of the present invention is to provide a clean constant-temperature constant-humidity system for an operating room which uses a corner space of an operating room to be installed, prevents an outside air duct from being exposed to the outside to easily manage infection prevention, and requires a short construction time to be easily applied to operating rooms of small and medium hospitals. To achieve the objective, the clean constant-temperature constant-humidity system for an operating room comprises: an operating space including a corner formed to have an angle between two walls within 180 degrees； a constant-temperature constant-humidity unit including two tight response surfaces tightly attached while facing the two walls forming the corner, and a rear surface connecting the two tight response surfaces to each other and being separated from the corner, wherein equipment for adjusting an air flow, temperature, and humidity is installed in a case for forming an outside air introduction passage with the walls forming the operating space； and a finishing member installed to be extended from the constant-temperature constant-humidity unit arranged on the corner to a ceiling of the operating space to close a space between the constant-temperature constant-humidity unit and the ceiling. The constant-temperature constant-humidity unit includes: a diffuser having a plurality of wings arranged in a circular structure and inclined in the same direction； an outside air duct embedded to have a structure connected to the outside air introduction passage； and an outside air damper installed on the outside air duct to open and close a flow passage of the outside air duct. The finishing member includes: a first finishing plate formed to protrude upwards from an upper end of the constant-temperature constant-humidity unit； and a second finishing plate coupled t
