In the present study, Taguchi method was employed for design of experiment of tertiary blended self-compacting mortar in order to optimize its compressive strength at the age of 28 days. Three admixtures including fly ash (FA), slag (S), and Nano silica (NS) were used to partially replace the Portland cement (PC). Three factors including FA (at 4 levels of 0, 10, 20, and 30%), S (at 4 levels of 0, 10, 20, and 30%), and NS (at 4 levels of 0, 2, 4, and 6%). By utilizing L16 Taguchi array, 16 series of experiments were conducted on the prepared specimens. The obtained results were evaluated by analysis of variance (ANOVA) method to determine the optimum level of each factor. To validate the accuracy of the optimum conditions suggested by ANOVA, compressive specimens were made and tested in accordance with the optimum conditions. It was found that the optimized compressive strength using Taguchi method was higher than those of proposed in initial 16 series. Water absorption and microstructure of the optimum mix along with some other mixes were also assessed for better validation and comparison which confirmed the improved properties of the mixture with optimized compressive strength.