The purpose of this study is to investigate the actual field application of the airless paint spraying pump driven by the hydraulic power unit under high pressure condition. The velocity and the pressure distributions are obtained using the turbulent k-ε model. The flow characteristics under design condition of spraying pump was numerically conducted by commercial fluid dynamic code(CFX ver. 13). The numerical analysis was performed by transient technique according to the variation of stroke times, which is changing from 0 to 1 seconds by interval of 0.01. Turbulence model, k-ω SST was selected to quaranty more accurate prediction of oil flow. The ICEM-CFD 13 and CFXMesher, reliable grid generation software were also adapted to secure high quality grid necessary for the reliable analysis. According to the simulation results, the flow rate was supplied to the paint spraying pump is 5l/min. These results are in good agreement with design results and could be applied to the design of the high viscosity paint spraying pump.