The carbon nano-tubes/potassium nitrate (CNTs/KNO₃) composites were prepared by recrystalization and neutralization method respectively. Micro-morphologies and thermal decomposition properties were characterized by scanning electron mitroscope (SEM), X-ray diffraction (XRD), specific surface area (SSA and differential scanning calorimeter (DSC). The results show that KNO₃ is coated on the surface of CNTs by two methods. SSA of the nano-CNTs/KNO₃ composites by recrystalization decreases about 113.9 m²·g^{-1<./sup> compared with that of CNTs, while the thermal decomposition temperature is the same as that of KNO₃. SSA of the nano-CNTs/KNO₃ composites prepared by neutralization decreases about 138.7 m2·g-1<./sup> compared with that of CNTs, and the thermal decomposition temperature decreases about 28 ℃ compared with that of KNO₃. Results show that in neutralization, CNTs has catalytic effect on the thermal decomposition of KNO₃.}