Composite materials have recently become widely accepted as a preferred structural material due to their customizable nature and improved thermal, strength, and durability performance. Carbon/carbon (C/C) composites are widely used in applications requiring high temperatures, such as rocket nozzle exits, missile leading edges, nose cones, and brake pads. Estimating the mechanical properties of C/C composites poses a challenge due to their complex microstructure. This paper focuses on the multi-scale structure model which includes a micro-scale and a meso-scale structure model with periodic boundary conditions to homogenize the heterogeneous fiber/matrix system into unit cells. At the microscale, two types of Representative Volume Element (RVE), namely hexagonal and square RVE, are analyzed to predict the mechanical properties of a fiber bundle. The effective properties obtained at the microscale are then utilized as input for the mesoscale. Scanning Electron Microscope (SEM) images are employed to model the meso RVE. This multi-scale approach allows for a comprehensive analysis of the mechanical properties of C/C composites, considering both microstructural details and overall material behavior. By bridging the micro- and mesoscales, the analysis provides insights into how the arrangement and properties of individual fibers contribute to the macroscopic behavior of the composite material.