An open type fine-tuning sight, including a housing mainly provided with a straight portion and a lens mounting frame, and the housing includes an outer housing assembly and an inner housing assembly; the inner housing assembly is sleeved in an installation space of the outer housing assembly, and a front end of the inner housing assembly is connected to the front end of the outer housing assembly through a parallel connecting rod assembly; a vertical return spring sleeved on a connecting screw is arranged between the rear end of a base and the bottom surface of the straight portion, an elastic sheet is disposed between one side of a rear end of the base and one side of a rear end of the straight portion, which are cooperated with a fine-tuning mechanism to realize the adjustment of the pitch angle and the lateral angle of the inner shell assembly.