To accurately obtain the optimal mix proportioning of cemented tailings backfill (CTB) for an iron mine, the slurrying water property, the weight ratio of tailings to binder (T/B) and the mass concentration of CTB were selected as influencing factors, and the compressive strength, the slump and the bleeding rate of CTB were selected as performance parameters. Based on the response surface-desirability function coupling theory, Box-Behnken design method was used to carry out thirteen groups of experiments with different mix proportioning. Then the effects of influencing factors on performance parameters of CTB were assessed and response surface functions of performance parameters were established. The results show that the slurrying water property has little effect on response variables. T/B has an extremely significant effect on uniaxial compressive strength after 28 days curing time of CTB, and slump is affected by both mass concentration and T/B at a more significant level. Moreover, T/B, mass concentration and their interaction have an extremely significant effect on bleeding rate. The optimal mix proportioning is that the slurrying water resource is seawater; T/B is 8.44 and the mass concentration is 72%. Under such conditions, the predicted values of response variables are 2.00 MPa, 27.15 cm and 7.35%, respectively, which are in perfect agreement with the confirmatory experimental results. The results of this research provide a more comprehensive engineering approach to CTB mix proportioning.