In this paper, tailings from Daye iron mine as aggregate, ordinary 425 # cement as cementing agent were adopted to make the filling samples in the test. Aimed at the three factors including cement-tailings ratio, curing age and slurry which influenced the strength of filling sample, single factor experiments were tested. Based on data analysis of the uniaxial compressive strength of 225 samples, it was shown that the compressive strength of filling samples was positively correlated with these three factors. According to the compressive strength of filling sample at 28d of age, the cement-tailings ratio of filling sample suitable for Daye Iron Mine was determined, which provided a theoretical basis for the choice of technical parameters of filling mining technology in Daye Iron Mine. Through the Scanning Electron Microscopy (SEM) experiments for filling samples with different ages, the composition of chemical elements and resultant of the samples of different ages were analyzed, and reasons for the strength differences between the samples at different age was obtained, and a useful probe was conducted about the reaction mechanism.