In order to study the distribution of the annular gap flow field during the bend start of the pipeline vehicle under different loading conditions. Numerical simulation combined with physical model test verification was used to study the annular gap flow field during the horizontal bend start of duct trucks with different loads. The results show that the increase of load does not change the overall distribution of the gap flow field velocity, but only changes the magnitude of the gap flow field velocity; Under different loading conditions, the axial flow velocity of the gap flow field of the pipe vehicle in the horizontal bend has the law of increasing and then decreasing from the inner wall of the pipe to the outer wall of the pipe vehicle. The circumferential flow velocity is more uniformly distributed at the section of the pipe vehicle gap inflow port and the section in the vehicle, but the opposite distribution of flow velocity on both sides of the sealing cover appears at the section of the gap flow outlet. The radial flow velocity is more uniformly distributed as far away from the support body and the seal cover, and the flow velocity increases significantly at the support body in the slit flow outlet section of the pipeline vehicle. This study explains the reasons for the formation of annular gap flow field distribution law and obtains the flow velocity distribution law of the gap flow field when the pipe vehicle is started at the bend with different loads. While improving and enriching the theory of annular gap flow, it provides theoretical basis for the application of hydraulic conveying in cartridge loading pipeline.