According to the characteristics of Chip-on-board (COB) packaging structure and considering the reflective cup structure and fluorescent powder coating methods, the main factors impacting the light emitting properties of a COB packaged Light Emitting Diode(LED) were analyzed. On the basis of the several key elements of reflective cup structure, indluding its shape, depth, and angle, this paper optimized the design of LED optical structure. By changing the relevant parameters of reflective cup in TracePro software, the light intensity distributions and output efficiencies of different LEDs were simulated, and the approach to improve the light luminescence properties of a COB packaged white LED was discussed. Finally, the contrast experiments on a traditional phosphor coating method and a coating method with phosphors away from the LED chip were performed under drive currents of 4 mA and 12 mA, respectively. The simulation and experimental results show that the luminous performance is more excellent in the reflective cup with a conical shape , a bigger depth in a certain range and a angle of 30 °. As compared with traditional packaging method, the coating method with phosphors away from the LED chip can improve the luminous efficiency by more than 5%. It has certain guiding significance for the LED packaging manufacturing process.