Abstract: The agricultural drought causes crop damage and failures, which in turn can also lead to food shortage problems and even famine. Drought risk is composed of the risk of disaster causing factor and vulnerability of disaster-bearing body, in short, it is not easy to control the risk factors and disaster risk only by reducing the vulnerability of disaster-bearing body. Therefore, it is of great significance to assess the vulnerability of the agricultural drought system in the agricultural drought risk management. Bengbu city is a big agricultural city in Anhui Province and even in China, with frequent droughts and serious drought damage. A vulnerability assessment model on the basis of an improved cloud similarity is established to assess Bengbu city agricultural drought system vulnerability according to the characteristics of the cloud model, and fully considering the uncertainty existing in the assessment process; and analyses are made through three digital features: expectation, entropy and the hyper entropy, providing a simple and effective method for quantitative analysis of the uncertainty of the agricultural drought system. The assessment results show that the expectation calculated by the comprehensive assessment method and based on the improved cloud similarity is the same as the result of a fuzzy comprehensive assessment. At the same time, there are two parameters: the entropy and the hyper entropy, reflecting the uncertainty including possible range of values, dispersion degree and stability; and the uncertainty of vulnerability and risk can be fully considered, which can provide a strong basis for drought risk regulation, control and management.