Nano-condensed carbon and nano-diamond were synthesized by explosive detonation, and their structures and properties was characterised by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM), scanning electron microscope (SEM), infrared spectroscopy (IR), electron paramagnetic resonance (EPR) and thermal analysis. Nano-condensed carbon was treated with various of acidic oxidizing solution in order to obtain nano-diamond, XRD studied showed that the best purifying effect can be attained using HNO3 at high pressure and high temperature. The influence of various factors such as preparation methods, condition of chemical treatment, size of particles, surface modification and impurity admixture on density of free-radicals of nano-condensed carbon and nano-diamond were also discussed. The Debye characteristic temperature and some other physics parameters were calculated according to X-ray diffraction intensities. The reasons of nano-diamond aggregation were discussed and a model is proposed. Furthermore, the nano-composites were prepared by low filling nano-condensed carbon or nano-diamond to polypropylene (PP). XRD, differential scanning calorimeter (DSC), SEM were used to study the crystallization behavior and mechanical properties of nano-composites. The result showed that the crystallization degree of the a crystalline form was increased and the tensile strength was improved, but the impact strength of the nano-composites was decreased.