Abstract: The synthesis of nanomaterials, e.g. carbon nanomaterial, is the cutting-edge technique and becomes one of the most significant foundations in the field of nanotechnology. In this review, we introduce the mainstream methods and recent progress of the carbon nanomaterial synthesis. The advances of plasma technology for synthesizing carbon nanomaterial, especially the liquid-plasma methods, are presented. The multi-factor synergistic effects of liquid-plasma on the carbon nanostructures are interpreted. And we summarize the quality, efficiency and growing mechanisms of the products synthesized by liquid-plasma processing under various conditions, including discharging parameters, catalysts and liquid types. The review brings forward perspectives and thoughts on the pathways of large-scale and high-efficiency synthesis of carbon nanomaterial.