The washing floodlight is a sort of optoelectronic equipment for the use on vessels which contain helipad, designed as a visual landing aid for the helicopter. Usually the washing floodlight is installed directly on the edge of deck, while the installation site should not be too high, normally lower than 350mm is recommended. In addition, since floodlight generally provides high and relative uniform illumination for a larger deck surface, it is necessary to have a reasonable light intensity distribution, high light intensity and high light energy efficiency. Meanwhile, the floodlight need to provide not only visible light but also infrared illumination to coordinate with night vision goggle. This paper provides a washing floodlight design with high light intensity and high average illumination. The illumination optical system consists of two separate portions, namely refraction and reflective illumination optical system. The refraction illumination optical system is a cylindrical lens with free-form surface, the upper part of lens is responsible for small angle illumination (about 0° to -5 ° in the vertical direction), while the nether part is responsible for large angle illumination (about -5 ° to -30 °in the vertical direction). Besides, the reflection illumination optical system is a cylindrical mirror with scaly conicoid reflection surfaces rather than traditional smooth quadric surface, which can improve the ability to control light, providing a larger angle of uniform illumination. In the later part of this paper, the illumination performance with 8 washing floodlight is simulated, and the illumination performance picture of a real washing floodlight is given.