3D printing technique has been developed rapidly and applied to manufacture components of diverse and complicated shapes and structures based on the computer-aided designs. To make 3D printing more promising and useful for more application purposes, mechanical properties of the materials used for printing should be studied and improved by developing new optimization methods. In this paper, a new optimization technique is developed for boosting mechanical properties of the materials by comparing tensile stress and extension of the specimens under different amount of loads in ANSYS. The specimens are made of two types of materials of various geometries and the same weight ratio according to the ISO mechanical test standards. Specimens are made of ABS and PLA. Case C shows the best tensile performances while Case B also shows good performs. Moreover, it is justified that the printing materials built of multi-materials have better properties, as well as the geometrical structures of the materials, influence the tensile performances of the materials significantly.