In the present work, the thermogravimetric analysis-Fourier transform infared spectroscopy (TGA-FTIR) system was employed to investigate the co-pyrolysis behavior of oil shale (OS) semi-coke (SC) and furfural residue (FR). Results indicated that the addition of furfural residue improved the pyrolysis characteristics of blends, while synergy behaved differently with the variation of the mixing proportion. Semi-coke could act as a catalyst for the furfural residue pyrolysis and facilitated the release of hydroxyl, but slightly inhibited the release of CO2 and CH4. The optimal blending ratio of oil shale semi-coke to furfural residue was 1:1. Besides, kinetic parameters were calculated using model-free methods, declaring that the sample pyrolysis was a multi-process.