Abstract: After twenty years of theoretical and practical research, the author proposes epistemology and methodology on prevention of geo-hazards in scientific philosophy. Geo-hazards are recognizable and can be controlled in epistemology. Since geo-hazards resulted from the unbalance of gravitational behaviors in soil or rock body, its commonality and particularity reflect different terms, such as geological body in the boundary, initial and excited conditions. For a specific situation, geo-hazards could be simplified to linear and definite problems which could be done in engineering control. Methodology for mitigation of geo-hazards can be used to obtain useful solution according to holism and reductionism, which promisingly use to develop the technical support system for public management of geological disasters reduction. The methods based on holism include synthesis, sum up, analogy, deduction, et al. Which can be applied to top or concept design of geo-hazards judgment in long time such as regional risk mapping, early warning and prevention plan. The methods based on reductionism include observation, description, analysis, modeling, evaluation, forecast and engineering control. It can be used to study area/case and its temporal state of slope problems, including geological information acquisition, identification of dangerous area and estimation, analysis of genesis, forecast or early-warning, analog simulation, project argumentation, risk assessment, decision-making support, et al.