Abstract: The field angle of f-theta lens used in laser marking system is generally less than 60. By adopting a telescope structure and using a method of visual magnification, a super wide lens with the field angle of 90was obtained in the optical system. The method is simple, reliable, and easy to achieve. Based on the analysis of primary aberrations, the parameters of initial structure were determined, and the ftheta lens with a large working area of 285 mm in diameter was obtained by optimizing the initial structure with ZEMAX. The linear distortion error of the lens is less than 1%, the energy concentration rate is 80% in the circle with a radius of 698 m and the focusing performance is diffraction-limited.