The polymerization of resin monomers was initiated in the presence of nanofibers as structural templates to prepare a hydrogel with nanofibrous networks, followed by the drying and pyrolysis to get hard carbon aerogel. During polymerization, the monomers deposit on templates and weld the fiber-fiber joints, leaving a random network structure with massive robust joints. Moreover, physical properties (such as diameters of nanofiber, densities of aerogels, and mechanical properties) can be controlled by simply tuning templates and the amount of raw materials.