In teaching a key curriculum, Mechanical Engineering Materials, in the discipline of mechanical engineering, reductionism and holism were applied. Besides the calculation of atomic packing factor, three key knowledge points were abstracted by applying reductionism, which were the model on bonding forces and energies of two isolated atoms, diffusion theory, and minimum-energy principle. Basing on these three key knowledge points, plenty of the contents in this curriculum can be understood easily and the learning efficiency can be elevated. Moreover, due to the deficiency of reductionism in analyzing complex issues, such as the influence of electric current stressing on the strength of materials and the ductile-to-brittle transition of a structure at low temperature, holism was applied concurrently. These applications can not only improve the teaching efficiency under a curriculum time shrinking condition, but also show students how to analyze complex issues.