A zoom functional optical lithography system with all spherical surfaces is designed. The system can automatically realize four zoom positions, and is comprised of two negative lens working as zoom group, two positive lens working as compensatory group to compensate the image surface shift induced by the conjugate distance change during the zooming motion. The system has an optical length of 653.67 mm with 22 pieces of lens. All the components are spherical surface and no special glass is employed. Under the 405 nm working wavelength, the modulation transfer function of this up-to-date lens is greater than 0.4 with 500 lp/mm at all four zooming positions and field of view and the absolute distortion is less than one sixth characteristic dimension. The result illuminates that the lens system design meets the requirement of good image quality and low cost for manufacture, and it can be applied in micrometer solution zoom optical lithography system.