In order to analyze the characteristics of the resistance in the transverse groove of pipelines, the standard k-ε model was adopted to numerically calculate and compare the resistances under the conditions of different velocities in ten groups of pipelines, and the impact of speed and groove shape on the drag reduction could be obtained through these numerical simulations. Based on all these analysis, the drag reduction mechanism of groove pipelines could be obtained, i.e., the low-speed fluid is regarded as a layer of water film, which makes the high speed fluid contacts with the inner wall of the tube, and the friction of the groove could be indirectly reduced. Therefore, the local fluid flow resistance will be decreased as the vortex zone within the groove becomes more regular.