To reduce the ultra-wide field angle, a pre-optics group that consists of several negative meniscus lenses of large power in a fisheye lens is used. The large incidence angle of light at these negative meniscus lenses will result in very serious aberrations. In the paper, the aspheric pre-optics design is proposed to control the aberrations of fisheye system. Based on the plane-symmetry imaging properties of the pre-optics, the evaluation function developed with the aberration theory of plane-symmetry optical systems is applied to optimize the aspheric coefficients of pre-optics surface as well as other parameters of the optical system. The imaging performances of different design options are evaluated with the evaluation function and ray-tracing simulation of Zemax.The results show that the fisheye lens optimized with aspheric pre-optics has significantly better imaging quality.