Abstract: With large density, high flow velocity and strong impact, river flood formed in loess area may scour riverbed, making the pipeline suspended. To evaluate the effect of flood on suspended section of river-crossing oil and gas pipeline in the area, considering the mechanics of the section, a mechanical model is built. Then, calculation and evaluation methods of pipeline failure risk are established according to the information entropy theory. Taking the suspended section of MaHuiNing Oil Pipeline as example, the effects of flood on pipeline failure in aspect of external diameter, wall thickness, internal pressure, suspension length and buried depth are discussed. Analysis results show that the changing curve of pipeline's strain energy entropy with the flood flow velocity can reflect the variation of the pipeline stability; the change of suspension length is has the most effects on pipeline failure risk coefficient, and the pipeline's internal pressure and buried depth have less effects on the risk. The pipeline's suspension length should be reduced in risk control to effectively reduce the failure risk.