Nano Fast Cement (NFC) is a nanocomposite with a short setting time for repairing root teeth canals as an alternative to Mineral Trioxide Aggregate. The downside of this new tooth restorative material is the poor workability and low compressive strength. In this study, polyvinyl alcohol (PVA), colloidal nano-silica, and hydroxyapatite nanoparticles were added to NFC to improve its physical, mechanical, and biocompatibility properties of NFC. The effects of the three additives on strength were determined. Experiments were designed based on the Taguchi method. The optimum contents of the three additives for the highest compressive strength, flexural strength were also obtained. The results showed that the most effective factor on the mechanical (compressive & flexural strength) properties of NFC is polyvinyl alcohol. Based on the Taguchi method, the optimal (highest value) of the mechanical property is obtained for PVA, nano-silica, and nano-hydroxyapatite contents of 6, .0.5, 0 Wt.%.