In order to improve the energy release characteristics of Al powder in composite explosives， combining the advantages of microstructure design and surface modification of Al particles， hexanitrohexaazaisowurtzitane （CL-20）/Al@Co/nitrated bacterial cellulose （NBC） composite with 3D network structure was prepared. Firstly， Al@Co particles were synthesized by coating Al with Co via the replacement reaction. Then， Al@Co and CL-20 particles were deposited into the 3D network structure of NBC to form CL-20/Al@Co/NBC composite with 3D network structure. The transmission electron microscopy （TEM）， scanning electron microscope （SEM）， X-ray diffraction （XRD）， X-ray photoelectron spectroscopy （XPS） and Fourier transform infrared spectroscopy （FT-IR） were used to characterize the morphology and structure of the composites. The properties were analyzed by thermal analysis， sensitivity test and combustion test. The results show that the Al@Co particles are formed by coating Co on the Al surface with a thickness of about 32 nm. The CL-20/Al@Co/NBC composite has a 3D network structure. Compared with the NBC+CL-20+Al mixture and CL-20/Al/NBC composite， the higher thermal decomposition peak temperature of Al in CL-20/Al@Co/NBC composite is elevated by 123.7 ℃ and 99.5 ℃， and the heat release is increased by 5.93 kJ·g^-1 and 4.50 kJ·g^-1， respectively. Moreover， CL-20/Al@Co/NBC has a shorter ignition delay time， faster combustion rate， lower impact sensitivity （30 J） and friction sensitivity （192 N）.