Abstract: Drought and flood disasters are the most important factors that restrict the development of agriculture economic. Drought and flood evaluation plays a vital role in the disaster mitigation decision-making. In this paper, according to the fuzzy uncertainty of drought and flood disasters and based on the variable fuzzy set theory, the relative membership degree of the sample index in standard interval of each grade was identified. Taking the drought and flood disasters assessment of Shandong province as an example, authors applied the fuzzy set theory with multi-parameters combination and variable model (one linear model, three non-linear models) to evaluate the disaster. The results confirmed that the sample assessment grades were reasonable. Compared with the other models, the model in this research was simple and reliable, and it provided a reference for drought and flood disasters evaluation.