Based on the method of LST/QST improved in the molecular orbital DMol3 program, with the aid of the minimum energy path (MEP) in the climbing image nudged elastic band (CI-NEB) method, the Oh-Al13 cluster is investigated under different synthesis process, i.e. Al6+Al7→Al13. The results show that: there are two stages in the synthesis reaction: the distortion stage and the configuration revolution stage. In the first stage, the metastable structures are forced to change into stable structures. In the configuration evolution stage, two different cases exist. For the synthesis of crystal clusters it is an automatic exothermic reaction if all reactants being of typical crystal symmetrical elements, i.e., Al6+Al7M®Oh-Al13. While an energy barrier must be overcome if one of reactants having fivefold or tenfold symmetrical axes, i.e.,Al6+Al7、Al6M+Al7 and Al6M+Al7M . So the five-symmetry structures are only appearing in rapidly solidified processes except crystallization processes.