Carbon coils could be synthesized using C2H2/H2 as source gases and SF6 as an incorporated additive gas under thermal chemical vapor deposition system. Ni layer on SiO2 substrate was used as a catalyst for the formation of carbon coils. Ni powder was evaporated to form Ni layer on the substrate. The characteristics (formation densities, morphologies, and geometries) of as-grown carbon coils on the substrate were investigated as a function of the evaporation time for Ni catalyst layer formation. By hydrogen plasma pretreatment prior to carbon coils synthesis reaction, the dominant formation of the nanosized wave-like geometry of carbon coils could be achieved. The characteristics of as-grown carbon coils with or without hydrogen plasma pretreatment process were investigated. The cause for the control of the carbon coils geometries from the microsized type to the nanosized wave-like one by H2 plasma pretreatment was discussed in association with the stress of Ni catalyst layer on the substrate.