The exhaust emission standards of vehicles using diesel fuel have been tightened for the prevention of air pollution. Therefore, this paper was carried out to study on the exhaust emission characteristics in the diesel engine with the Urea-SCR system according various urea contents rate. In order to analyze the emission characteristics, the diesel engine with six cylinders (7.6L) with the high pressure common-rail was used and it was applied to urea-SCR systems. In addition, the urea contents of six cases (0, 30, 32.5, 35, 37.5, 40%) were used to investigate the exhaust emission characteristics in the Urea-SCR system. To analyze the exhaust emission, the MEXA-7200D (Horiba) was used and FTIR (Horiba, MEXA-6000FT) was applied for the analysis of NH3. From this study, it is revealed that the NOx emission was significantly reduced as the urea content rate was increased until the 30%. However, the decreasing rate of NOx emission shows a slight steady reduction over the 30%. On the other hand, the NH3 amounts show the increasing patterns according to the using urea water with high urea content rate.