The effects of Sr addition on mechanical properties and microstructure of aluminium ADC12/Nano-SiC composites produced by stir casting have been investigated. The addition of Sr into ADC12 matrix was varied from 0.01 to 0.03 wt.% and the other elements added were Al-5TiB as a grain refiner and Mg as a wetting agent. It was found that the phases present in composites analysed by Scanning Electron Microscope link to Energy Dispersive Spectra was Mg2Si primary, Mg2Si binary, β-Al5FeSi and Al2Cu respectively. The results show that Sr modifies acicular/plate like of Al-Si eutectic into fibrous. Sr also reduced slightly the average size of blocky Mg2Si primary and changed Chinese script of Mg2Si binary into polyhedral or finer fibrous shape. The modification effect plays role in improving mechanical properties. The highest optimum UTS and elongation were obtained at composites with 0.025 wt.% Sr with the value of 292 MPa and 1.88% respectively, while the SDAS was 11.85 µm. The hardness and wear rate of all composites were relatively no changed.