Abstarct: Tailings production is going to increase due to world’s population growth, high demand and consumption of mextals and minerals, ore deposits with low grade and quality and new mineral processing technology. Tailings dam failure causes catastrophic result to the environment and high cleanup cost. In this study, the implementation of risk analysis of tailings dam failure is used to predict the probability of tailings dam failure and its consequences. In this study, the reasons and the results of more than 300 tailings dam failure, between 1914 up to 2015, are studied. The important factors of tailings dam failure are recognized baxsed on the studied tailings dam failures. These 24 factors are classified into four failure mechanism and the weighs and the performances of factors are evaluated using Preference Voting System (PVS) method. The mechanism and their weighting results namely are: slope failure by 48.9%, overtopping failure by 23.7%, piping failure by 20.4% and foundation failure by 6.9% respectfully. As the analysis of tailings characteristics is vital for tailings dam failure analysis, the most important characteristic such as tailings void ratio, consolidation rate, pore water pressure and shear stress are studied for Sungun copper mine of Iran. The results of comparison between Sungun tailings characteristic and other copper mine’s tailings, indicated the similar range of change. The new degree risk method of failure is developed baxsed on weight and the probability of dam failure due to each failure mechanism. The probability of failure is estimated using structural reliability analysis and elements in factor of safety. The elements in factor of safety for slope stability of tailings dam failure is modified by considering the shear stress of tailings materials. The Monte Carlo simulation is applied to evaluate the probability of failure. The modified Folchi method is applied for the consequence evaluation of tailings dam failure. The consequence of failure is classified in to three category baxsed on the criteria of sustainable development namely social, environment and economy. Cost-Benefit analysis is used for prediction the economic consequence of tailings dam failure considering the benefit of tailings dam reclamation (forestry reclamation) and the cost of dam break and cleanup. The proposed methodologies are applied for Sungun copper mine. The results of this study shown that the probability of tailings dam failure in Sungun, due to slope failure 67.3 %, overtopping 64 %, foundation failures are zero. In this investigation, the results indicated that the probability of failure due to slope instability or structure failure is in dangere zone. Overtopping failure is in high risk in unpredictable raining weather. The consequence of failure using modified Folchi method indicated that in the case of Sungun tailings dam failure, the consequences are, economy 100%, social 80 % and environmental 65% which catastrophic result of will happen.