Abstract: In order to more accurately detect pipeline leakage and predict the impact of leakage on pipelines, considering the influence of oil heating treatment, this paper analyzes the flow field characteristics of tiny leaks with different pore diameters in oil pipelines, and establishes simulation models with different pore diameters. It also analyzes the influence of heat treatment on the leakage flow field, and judges the necessity of heat treatment. Under the condition of heat treatment, the characteristics of the leakage flow field with different pore diameters are compared and the variation rule of the flow field is analyzed. The research results show that heat treatment will lead to changes in the viscosity of oil, and then bring significant changes to the pressure and flow rate of oil pipeline leakage holes, so it is necessary to consider the influence of heat treatment on leakage.Under heat treatment conditions, the three small leaks with different pore diameters have little effect on the flow field characteristics inside the pipeline, but at the leak hole, with the increase of the pore diameter, the pressure decreases and the flow rate increases.