In this work, the effect of sodium chloride (NaCl) powder addition with different amounts on microstructure and mechanical properties of Al-12 wt. %Si alloy was investigated. In this technique, modification by NaCl was used because of its availability and low price comparing to other modifiers such as Sr and Sb. A 1000 °C as pouring temperature of molten alloy was used. The present results showed that there is a significant change in the mechanical properties and microstructure compared with unmodified alloy. The optimum properties were found by adding 0.5wt% NaCl to the alloy, and also the modification of microstructure alloy. Mechanical properties and microstructure of Al-12wt. %Si alloys that poured from 1000 °C with NaCl additives were compared with the corresponding alloys but at 800 °C pouring temperature, it is found that alloys poured from 1000 °C have best properties as compared with the same alloys poured from 800 °C.