The solution redistribution was an important phenomenon during the solidification of multi-component alloys. The different paths of solidification of different component Al-Si-Mg alloys were calculated in this paper. The calculations were coupled with CALPHAD technology. The interaction of solutes would change the solute redistribution coefficients during the solidification especially in the ends of solidification. The solidification paths were calculated by employing the CALPHAD technology and the binary partition coefficients separately. The results show that errors exist under assuming the partition coefficients of solutes as a constant due to the interaction between solutes in ternary alloys. The predicted solidification processes of Al-Si-Mg alloys agree well with the experimental results in this paper.