In this study, Application of sequencing batch reactor (SBR) process for RO retentate treatment was performed. Efficiency of treatment by load and temperature variation was tested. The SBR process was operated two types as HRT per one cycle was 8 and 12 hours, respectively. Methanol was injected for an effective denitrificaion owing to low C/N ratio of the RO retentate. TN removal efficiency of the SBR process was relatively stable at the change of flow-rate and temperature. The optimum time cycle of SBR process was 2 cycle/day for TN removal, and in the case of 3 cycle/day, the effluent TN concentration was found under the effluent quality standard. In the result of assessment, the application of SBR process for RO retentate treatment was effective and could be utilized to design for the wastewater treatment plant. The specific nitrification rate (SNR) and specific denitrification rate (SDNR) were $0.043{sim}0.066kg;NH_3-N/kg;MLVSS{cdot}day$ and $0.096{sim}0.287kg;NH_3^--N/kg;MLVSS{cdot}day$, respectively. The derived kinetic could be applied for design to the aerobic and anoxic tank in the RO retentate treatment.