Ultraviolet microscopic measuring system has been widely used in bioscience and semiconductor industrythe tube lens is an important part of the infinite conjugate microscopic system. For the contradiction between the requirement of zoom function and the accuracy of focal lengththe design of a near ultraviolet-visible triple focal length tube lens system with high resolutionwide field of view (FOV) and low distortion was introducedwhich has working wavelength range of 355~500nm. The structure is special in that it is composed of common-path formal component and parfocal rear componentthe focal length can be changed accurately by replacing the rear component. The tube lens system was designed and optimized by ZEMAX and their aberration and MTF were analyzed. The design result of this system shows that the MTF of each FOV all approaches the diffraction limit at 70lp/mm in three focal length modes. The distortion is less than 0.5% with high relative illuminance of image plane. The system can satisfy the design index well under reasonable tolerance parameters and can be adapted to varieties of ultraviolet microscopic objective lenses for accurate microscopic measuring imaging.