A thermodynamic modeling for the A1-Mn-Si system is conducted via two steps. In the first step, all of the experimental phase diagram and thermodynamic data available from the literature ate Critically reviewed. and several isopleths are constructed by means of X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques. In the second step, a consistent thermodynamic data set for the A1-Mn-Si system over the entire composition and temperature ranges is obtained by consideling reliable literature data and the present experimental results. Numerous comparisons between the calculated and measured phase diagrams as well as thermodynamic quantities indicate that almost all of the reliable experimental information is satisfactorily accounted for by the thermodynamic modeling. The liquidus projection and reaction scheme for the entire system are also presented.