Abstract: With the abnormal global climate situation, local extreme heavy rainfall occurs frequently and the flood prevention work of small reservoirs in China is full of challenge. Therefore, it is necessary to carry out the dam breach risk analysis for small reservoirs. In this paper, a case study of a small reservoir in Shandong Province is presented and the impact on the downstream high speed railway under two scenarios of check-flood and dam-breach-flood is analyzed. The results can provide decision support for the relevant management unit to deal with the flood risk of dam breach.