According to the characteristics of the spiral groove tube lines，to the oil for medium, the three-dimensional spiral groove line of physical and mathematical model were built up, using SIMPLE algorithm, the flow process of the single-phase oil medium in three-dimensional spiral groove grain tube numerically was simulated. Using Realiable k-ε model for the turbulence model, revealed the flow pattern of oil by the influence of spiral groove in grain. The simulation results show that oil in the spiral groove grain tube exchange heat mainly by the way of strengthening the disturbance near the surface layer of fluid, heat exchange inside the tube is strengthened. It simulates the rate of the resistance loss coefficient of spiral groove grain tube and that about smooth tube which is about 4, which experimental data error is smaller. The simulation provides certain theoretical basis to optimize for heat exchanger design parameter which using oil for medium, and to improve the heat transfer efficiency.