The utility model provides a smoke concentration analysis meter optical-mechanical system with a deuterium lamp fine adjustment mechanism. The smoke concentration analysis meter optical-mechanical system comprises an ultraviolet source emission set, a collimating lens set, a gas pool set and an ultraviolet light receiving set. Three holes are formed in the front side of a deuterium lamp chamber, and threaded holes are formed in the two sides of the deuterium lamp chamber and used for allowing jackscrews to be screwed in. A through hole is formed in the middle of the deuterium lamp chamber, a threaded hole matched with the through hole is formed in the corresponding position of a deuterium lamp holder, and a connecting screw is screwed in the threaded hole. According to the system, the optical fiber receiving position where ultraviolet light enters can be adjusted accurately, smoothly and conveniently through the design of the deuterium lamp holder capable of being finely adjusted and a universal bulb type comprehensive reflector holder capable of being finely adjusted; meanwhile, the system achieves fast, reliable and stable detection of spectrograph dark currents through the ingenious design of an automatic and controllable diaphragm.