Since the construction method of tailings dams determines the uneven distribution of tailings, a reliability theory is introduced to analyze the stability of tailings dams. Based on the limit equilibrium method and reliability theory, the sensitivity and reliability of a typical tailings dam are analyzed. Reliability analyses with different types of the variable probability distribution types show that the effect of the probability distribution type on reliability analysis can almost be ignored. Besides, the sensitivity analyses of different variables show that the strength indexes and density of tailings will affect the analysis results of stability reliability. Therefore the strength indexes c, φ and density ρ must be considered as basic variables to analyze the stability reliability of tailings dams.