In order to reveal the relationship between the process and structural properties & failure mechanism, the influence of typical process parameters on the mechanical properties and failure mechanism of fused deposition modeling (FDM) composites was studied based on the experimental method, and the optimized printing process parameters were proposed. Meanwhile, based on the hierarchical multi-scale theory, a high-fidelity finite element model containing typical defects such as voids and resin-rich regions was established, and a method for predicting the macroscopic tensile properties of composite component was presented, the results of which were thereafter compared with its experimental counterparts. The results show that the filling rate of printing resin has a significant effect on the properties of the component. When the filling rate increases from 50% to 100%, the tensile strength of the specimen increases by 47.6%; when the layer thickness increases from 0.2 mm to 0.4 mm, the tensile strength decreases by 51% and tensile modulus decreases by 21%, while the influence of printing temperature and printing speed on tensile strength is relatively slight. The relative error of tensile modulus calculated based on the multi-scale finite element model is 2.73%, demonstrating its ability to accurately predict the mechanical properties of the composite structure by additive manufacturing.