Abstract: Carbon fiber reinforced polyetheretherketone (CF/PEEK) composites prepared by fused deposition modeling (FDM) have broad application prospects in aerospace and other fields, but the inherent defects of the FDM process lead to unclear mechanical behavior and damage mechanism. This study focuses on a 10% volume fraction short-cut CF/PEEK composite, systematically investigating its monotonic tensile and cyclic tension-compression behaviors under various temperatures, strain rates, and strain amplitudes. Microscopic characterization via scanning electron microscopy (SEM) is employed to explore the material's uniaxial mechanical response and damage mechanisms. The results showed that the stress-strain curve of the composite under uniaxial tension presented three typical stages: linear elasticity, yield softening and steady-state flow. Its mechanical properties were significantly affected by temperature and strain rate; the increase of temperature led to matrix softening, which reduced the material strength and stiffness, and the failure followed a progressive mode of "interface weakening-matrix failure-fiber fracture". Under cyclic tension-compression loading, the ε-N fatigue life curve of the material had obvious three-stage characteristics, cyclic softening was significant under medium and high strain amplitudes, and the damage was mainly dominated by interface fatigue debonding, matrix microcrack propagation and interlayer shear slip. The low-cycle fatigue life predicted using the Manson-Coffin equation falls within two times the scatter band. Numerical simulation of its mechanical response was carried out based on the Chaboche model, and the relative fitting errors of the stress-strain curves of uniaxial tension and fatigue steady-state loop were 3.34% and 4.82%, respectively. This study clarifies the mechanical response rules and damage evolution characteristics of FDM-processed CF/PEEK composites under complex loads, and provides reliable theoretical and experimental support for their engineering application in aerospace and other fields.