Gully erosion is an important type of soil erosion and is considered the dominant sediment source in small watersheds. Accurately predicting the spatial distribution of gully erosion and spatiotemporal variation of erosion intensity is critical for optimizing soil and water conservation measures in small watersheds, promoting regional food production, and maintaining regional ecological security. Topographic threshold models, susceptibility assessments, morphological features, erosion prediction models, and landscape evolution models are the main techniques for the location prediction of gully initiation, probability evaluation of gully erosion, and estimation of gully erosion intensity. Based on the fundamentals and principles of these methods, the findings of related studies are systematically compared and reviewed, and the advantages and disadvantages of each method are determined. Future research should focus on the optimization of gully measurements and the accumulation of monitoring data, the processes of gully erosion and the comparability of related data, the selection of prediction models and their applicable regions, the development of empirical models and variability of related parameters among various regions, and the gully erosion mechanisms and the development of process-based gully erosion models. Therefore, the proposed research provides technical foundations for mitigating gully erosion and insurance for sustainable development of regional society and economics.