Abstract: Recently, high power multi-chip chip on board (COB) LED has become the industrial trends, duo to its advantages, such as higher packaging density, higher thermal stability, wider irritation angle and etc. However, low light extraction efficiency of COB LED restricts its application and development. In order to improve the light extraction efficiency of LED, the models of COB LED packaged by cone arrays, half-ellipsoid arrays, rectangular pyramid arrays and hemisphere array were established and investigated by applying stimulation software. The stimulation result showed that under optimal conditions, the luminous flux of COB LED with 0.9 mm height and 0.5 mm diameter cone array lens increased from 67 lm to 84.3 lm, that is, light extraction efficiency increased by 25.8%. Finally, LED samples with RGB multi-chips were packaged by 1 mm diameter hemisphere array, and the light extraction efficiency increased by 18.8%.