Short-fiber-reinforced composites are widely used in a number of industries and applications, including in the transportation industry, and in business machine, durable consumer items, and sporting goods. Properties of fiber-reinforced composite depends on its fiber orientation distribution. Thus, knowing the fiber orientation is of great importance, and a number of researchers have been interested in developing useful and accurate techniques for determining the fiber orientation in injection-molded parts formed from short-fiber composite. However, out-of-plane orientation was preformed manually and difficulties arise when employing the technique in the case of composites with high fiber contents, over 50 wt%. In this research, short-glass fiber-reinforced polyamide 6 specimens produced using two different plate-shaped cavities having three different thicknesses ranging from 2 mm to 4 mm and with the fiber contents ranging from 30 wt% to 65 wt% are carried out using injection molding. The three-dimenstional (3D) fiber orientation observation and measuring are examined by Micro-computed tomography system Y.Cheetah μHD which cooperated with a calculation software using a calculation model (ex. Monte-Carlo Model). Herein, detailed 3D fiber orientation distribution from skin to core at different locations in high filler content composite specimens is automatically, and fast clarified. This novel measurement methodology may enable us to evaluate the ability of new model theory, the effective of implementation procedure for fiber orientation and mechanical property prediction in injection-molded composite.