Three-dimensional (3D) carbon nanomaterial assemblies are of great interest in emerging applications including electronic devices and energy storage because of their extraordinary high electrical conductivity, mechanical and thermal properties. However, the existing synthetic procedures of these materials are quite complex and energy-intensive. Herein, a facile approach is developed for fabricating a self-entangled carbon nanotube (CNT) network under convenient conditions (400 ℃ for 1 hour), breaking the critical limitations of the current available methods. The keys of forming such 3D CNT network are the fragmentation of the sacrificial MOFs into nano-sized particles, the reduction of metal elements in MOFs to highly active nanocatalysts by introducing hydrogen, and the supplement of external carbon source by introducing ethyne. In addition, the highly conductive 3D porous CNT network facilitates electron transfer and provides an excellent platform for high-performance Li-ion batteries (LIB).