According to the problems of high price of the ultra-thin LED panel l ight,high thickness and large quantity of LED for traditional direct-down LED panel light,a new direct-down LED panel light source is designed.The light source and target plane are meshed to form the mapping relationship based on the edge-ray theory.The differential equation of inner and outer freeform-surface is deduced on the bas is of Snell formula,and the corresponding data of freeform-surface are calculated by using the iteration me thod.The secondary optical lens with large view angle for the new direct-down LED panel light is designed.Rese arches show that the double freeform-surface lens with large view angle can realize large angle light distr ibution with 150°,the illumination uniformity is 0.86,and the energy utilization is 99.5%.When the distance-heig ht ratio (D/H) of LED array for the secondary optical lens with large view angle is approximately equal to 3,the il lumination uniformity of the target surface is above 0.88under different thicknesses.The new direct-down panel lig ht illumination is simulated.The results completely conform to the national building lighting standards.In addit ion,the number of used LEDs is 30% of that of traditional panel light sources under the same power,and the thic kness is reduced by 20mm,greatly cutting down the production cost of LED flat light.