According to the problem of low extraction efficiency and high manufac turing price of light guide plate (LGP) of edge-lighting LED flat panel light,a new designing method of LED flat panel light which is window type structure and without LGP is presented,and the structural model and optical model of the LED flat panel light are introduced in this paper.Cyli ndrical lens is used to make the divergent beam convergent,which comes from the edge of LED ligh t source,and the method of gazing and superposition are used to realize uniform illumination of the light pane.The intensity distributions affected by the distance b etween the LED arrays and the LED projection angle or the space between LEDs are analyzed.Optical simulations of the LED flat panel light designed based on squared figure value method,combined with TracePr o are performed to realize parameter optimization,and the projective angle of LED ligh t pearls is around 4° after parameter optimization.Simulations and experiment reveal that when an ar ea of one window of LED flat panel light is 240mm×300mm,and its thickness is 15mm,the curvature radius of flat convex cylindrical lens is 4mm,and the uniform illumination of t he LED flat panel light is above 85%.And the theoretical simulation results are con sistent with the experimental results.