Abstract: This study addresses the issue of poor mechanical performance of composites due to severe aggregation of graphene in metal matrix. Organic solvent polyether amine (PEA) was used for in-situ surface modification of graphene oxide nanosheets (GONs) to synthesize graphene oxide monomers (GOMs). GONs/TC4 and GOMs/TC4 composites were fabricated via ultrasonic stirring and spark plasma sintering. The research investigated the microstructure and mechanical properties of TC4 matrix influenced by GONs and GOMs, and explored the fracture behavior and strengthening mechanisms of GOMs/TC4 composites. The results indicate that compared to TC4 alloy, the matrix structure of GONs/TC4 composites was refined, forming layered TiC particles, with a length of about 15.0 μm. In contrast, the matrix structure of GOMs/TC4 composites exhibited more pronounced refinement, with higher density and equiaxed TiC distribution within the matrix, indicating significant improvement in the dispersion of GOMs in the TC4 matrix. PEA modification of GONs significantly enhanced the mechanical properties of TC4-matrix composites, with the tensile strength of GOMs/TC4 composites reaching 1054.0 MPa. This represents a 20.6% and 6.0% increase compared to TC4 alloy and GONs/TC4 composites, respectively. Moreover, the GONs/TC4 composites maintained a high elongation at break (~ 8.0%) and exhibited ductile fracture characteristics. The primary strengthening mechanisms of GOMs/TC4 composites were grain refinement and load transfer strengthening through GOMs.