In this study, the luminance, luminous efficiency and address time of an PDP as a parameter of the phosphor thickness and the size of discharge space are investigated. The maximum luminance and luminous efficiency are obtained at the phosphor thickness of 30 ${mu}{ extrm}{m}$ for the rib height of 110 ${mu}{ extrm}{m}$. For the rib height of 120~160 ${mu}{ extrm}{m}$, the maximum values are obtained at the thickness of 50 ${mu}{ extrm}{m}$ regardless of the kind of R, G and B phosphor. These results do not affected by the variation of discharge space. The average decrease rate of the total charge to the phosphor thickness is about 3.35pc/cell/10 ${mu}{ extrm}{m}$ and the average increase rate of the addressing time is about 0.027 $mutextrm{s}$/10 ${mu}{ extrm}{m}$.