The present development of Field Emission Display (FED) is restricted by the efficiency of field emitters and the quality of phosphors. Most phosphors have low luminous efficiency at voltages below 3 KV due to the low electron penetration depth and electrical charging of the phosphor surface. In this study, three different field emitters and one green phosphor with different concentration are investigated as the cathode and phosphor respectively. The optoelectronic properties of devices are discussed under varied voltage from 700V to 1,300 V. The best green device achieved has the luminescence as high as 5257 cd/m2 under the low driving voltage (1200 V).