The solidification microstructure of Mg-Ag-Ce-Zr cast alloy (QE22) was investigated. First, the thermodynamic simulation was performed using of JMatPro software. Then, for experimental experiments, melting, alloying and casting operations were performed using a low pressure casting machine under argon atmosphere. Also for T6 heat treatment, the samples were heated at 525 ° C and then quenched in water and aged at 200 ° C. In order to the microstructural and phase investigations, the optical microscopy and scanning electron microscopy (SEM) equipped to EDS analysis and X-Ray diffraction apparatus were used. Hardness measurements carried out using Brinell indenter. The results showed that the solidification microstructure of magnesium alloy with 2. 24% by weight of silver, 1. 52% by weight of alkaline elements and 0. 55% by weight of zirconium including 94 vol. % magnesium base phase (matrix) and 6 vol. % of eutectic cells. The results of EDS analysis showed that unlike zirconium, silver and alkali metals have significant solubility in the matrix, and as a result enriched intermetallics with zirconium and silver appear in the grain boundary or interdendritic area. It has also been observed that hardness of the alloy has increased from 43 to 48 HB by solution and aging heat treatment (T6).