Abstract: In order to study the failure probability of adjacent gas pipelines under the erosion action of water-sand jet, the influence of critical strain of pipe and plastic ridge formed by sand particles on the surface of pipe was analyzed, and the prediction equation of erosion wear rate was deduced. Then, the distribution of leakage jet rate and erosion area of water pipe was simulated and calculated by means of Fluent software, and the erosion wear rate equation was constructed based on the prediction equation of erosion wear rate. Finally, a method for calculating the failure probability of gas pipeline was established based on the criterion of minimum wall thickness. It is indicated that the critical spacing under different internal pressure and erosion time can be obtained by judging and analyzing the critical spacing. In addition, the increase of internal pressure, erosion time and sand particle size, and the reduction of pipe spacing and pipe wall thickness can increase the failure probability of gas pipeline. And among them, the effect of pipe spacing on failure probability is the most significant. The research results can provide reference for the quantitative risk assessment of failure scenario and the spacing design of water and gas pipelines laid in parallel.