Carbon nanotube(CN) layer was formed as a cathode next to the p-deciphenylene emitting layer in the ITO/p-deciphenylene(P10)/Al electroluminescent device (ELD). The two devices have the same blue EL emission peak at about 450nm. The Current density-voltage-luminance (J-V-L) characteristics were measured for the two devices and compared each other. The ITO/P10/CN/Al ELD has higher luminance than ITO/P10/Al ELD at lower current densities. The quantum efficiency (QE) behavior for the two ELDs are nearly the same. CN cathode layer induces easy electron injection by lowing the barrier height due to its low work function.