This study aimed to investigate co-torrefaction followed by co-combustion of intermediate waste epoxy resins and fir in the form of mini-pellet to evaluate the potential of industrial wastes as biofuels for alternatives of coals. Co-torrefaction and co-combustion of the materials were analyzed through thermogravimetric analysis (TGA) coupled with Fourier transform infrared (FTIR) spectrometer. The results suggested that most of the torrefaction had a slight influence on the wastes due to their thermal resistance properties. Conversely, fir was markedly affected by torrefaction, and the corresponding volatiles were the chemicals stripped or reacted from its components (hemicellulose, cellulose, and lignin). By introducing an index, both antagonistic and synergistic effects were discovered in the two-stage reaction because new compounds formed during the co-torrefaction and co-combustion processes, as a consequence of catalytic and blocking effects. Overall, co-torrefaction could make the quality of the biofuel from intermediate waste epoxy resins more homogeneous and is a promising route to transform waste epoxy resins into alternative fuels for industrial applications.