In order to investigate further the compaction characteristics of the three-dimensional four-direction preform of carbon/carbon composite, a model of three-dimensional four-direction numerical preform at the micro-scale was established using the programming language in Python based on the ABAQUS simulation platform more realistically to reflect the micro-structure of the preform. A model of three-dimensional fiber numerical growth was built to describe the changes of fiber bundle cross-section under compressive load considering the random distribution, deflection, bending and the physical characteristics of fibers not penetrating each other in three-dimensional space. In addition to exploring the characteristics of the fiber bundle compaction process in the inter-laminar dimension, the interaction between laminated fibers of the preform was analyzed; the method of finite element was employed to construct a compaction model of the three-dimensional four-direction preform; the deformation of inter-laminar fibers under compressive load was studied by the numerical simulation method; the nonlinear mapping relationship between compressive load and compaction height consistent with the preform compaction experiment was obtained. The results demonstrated that the deflection coefficient of the numerical model was 0.32, which was most consistent with the actual result.