The chemical kinetics of laser pyrolysis of Si(CH3)2Cl2 was studied. Besides Si/C deposited on substrate as a needle the main gaseous products were H2 and HCI. The decomposition rate constants of Si(CH3)2Cl2 and the formation rate constants of H2 and HCl were measured. The chemical and physical properties of the Si/C needles were studied by various methods, such as their outer features, elemental analysis, Auger depth profile spectra, X-ray diffraction. Other useful properties, such as electric resistivity, photovoltaic effect and hardness, were also reported. A model for the pyrolysis and the growth process of this Si/C needles was proposed. It should be emphasized that the samples with desired physical properties could be grown by controlling the growth conditions properly -- the laser power and the pressure of Si(CH3)2Cl2.