In this study, research has been done on the compressive and tensile strength of cement mortar containing 1, 3 and 5 percent by weight of cements Fe$_2$O$_3$ nano-particles. The results show that the mechanical properties of samples containing 1 and 3 percent Fe$_2$O$_3$ nano-particles is desirable then the ordinary cement mortar. SEM study about the micro structure of cement mortar containing nano particles and ordinary cement mortar showed that Fe$_2$O$_3$ nano-particles fills the pores completely and reduces the mixture of Ca(OH)$_2$ with hydrates and increases the final density of the prepared samples. The mechanical properties results showed that by increasing iron oxide nano-particles the mechanical properties enhances to 5 percent.