The morphology and growth mechanism of carbon nanotubes(CNTs) and carbon nanospheres (CNSs) produced by in-situ CVD method on different substrates were investigated using scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS) technology. The experimental results show that the growth of carbon-nano-material has great substrate independence during in-situ CVD process. At the same reaction conditions, CNTs with diameters of 60-140nm and CNSs with diameters of 150-450nm were synthesized on the 1K carbon cloth and graphite paper substrate, respectively. Based on the experimental results, a probable growth mechanism was presented for different carbon substrates. The explanation for the formation process is the difference of the concentration gradient and growth rate in the catalyst.