Multi-walled carbon nanotubes (MWCNTs), which has been studied as a heat conduction material, has excellent thermal properties, with thermal conductivity value of 3000 W/m·K. This study aims to reduce the thermal resistance of MWCNTs–buckypaper (BP) as a thermal interface material (TIM). Three methods are used in this experiment: ultrasonication, oxidation, and the addition of cellulose nanocrystal (CNC). The oxidation process is to remove impurities, which when prepared as a suspension, disturb the particle dispersion, and reveal a tendency to agglomerate. Therefore, a strong acid treatment removes impurities, and improves the dispersibility of nanofluids. The third method, the addition of CNC, which has been in the limelight recently, can affect structural stability, is eco-friendly, and is used for composite material synthesis with high tensile strength. These preeminent effects of CNC help improve the thermal resistance of CNC/treated CNT (C–tCNTs) mixed buckypaper. The thermal performances of TIMs used an ASTM D5470 standard tester, and various ratios of BP were tested using thermal resistance test. BP manufactured by adding MWCNTs and CNC had a resistance value of 0.776. This provided a 33.1 % decrease, compared to the oxidized MWCNTs BP. As a result, it was confirmed that CNC–CNTs BP has the possibility of being applied as TIM.