In this study, HDP(High Differential Pressure) and LDP(Low Differential Pressure) bipolar plates which had difference from inner pressure was designed for analyzing the correlation about differential pressure and performance of stack. The increase of inner pressure different was shown by increasing of flow rate according to current density about 1kW class stack using the designed bipolar plates and the inner pressure of stack was lower than unit cell. The anode inner pressure of HDP stack was 1.0, 1.4 and 1.7 kPa on SR(Stoichiometric Rate) 1.5, 2.0 and 2.5, respectively. Also, cathode side appeared to 9.0, 11.8 and 14.9 kPa on SR 2.0, 2.5 and 3.0 at 1,000mA/cm². The LDP stack was shown as inner pressure of sextuple compared with HDP stack. The performance of 1kW class HDP stack and LDP stack was 0.585 V and 0.593 V on average voltage of each cell at atmosphere pressure, anode SR 1.5, cathode SR 2.0 and 1,000mA/cm². These results showed that LDP stack with low inner pressure were superior to HDP stack about power consumption of BOP(Balance of Plant) like compressor and blower. However, performance of LDP stack at low current density was decreased by channel flooding. To supplementation of this phenomenon, increase of flow rate was necessary to stable operation of LDP stack.