A three-dimensional computational fluid dynamics (CFD) model of a diesel engine combustion chamber was developed using CONVERGE 3.0 software, with coupling to a detailed chemical kinetic mechanism containing 182 reactions and 52 components implemented in the CHEMKIN program. The model was employed to investigate the effect of injection angle on in-cylinder pressure, temperature and emission characteristic in a methanol-diesel mixed fuel engine. The results showed that the fuel jet axis was oriented closer to the combustion chamber boss at the injection angle θ=60°, leading to substantial fuel accumulation on the piston bowl surface. This resulted in suboptimal air-fuel mixing and promoted soot formation due to locally rich mixtures. In contrast, improved spatial distribution of the fuel spray enhanced mixture homogeneity under the condition of θ=75°, resulting in more complete combustion and peak in-cylinder pressure and temperature values. As the injection angle increased further, NOx and N2 emissions first increased and then decreased, and showed obvious inflection points. Meanwhile, HCHO emissions showed a continuous downward trend.