In this work, we demonstrate a simple method to prepare carbon nanofiber (CNF) with multilevel gradient porous structure derived from polyvinylidene fluoride (PVDF)-polyvinyl pyrrolidone (PVP) /PVP core-shell nanofiber. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have confirmed that the as-prepared CNF contains a hollow channel embraced by mesoporous and microporous structures. Its specific surface area reaches to 1084 m(2)/g with the mesoporous volume contribution of 59%. The as-prepared porous CNF shows a high capacitance of 331 F/g at 1 A/g and 99.6% capacitance retention after 10,000 cycles at 5 A/g, which is better than the corresponding CNF with irregularly arranged hierarchical pores. The all-solid-state symmetric supercapacitor assembled using the as-prepared porous CNF as electrodes exhibits an excellent high specific capacitance of 147.4F/g at 1 A/g with a high energy density of 13.1Wh/kg. The capacitance retention still maintains at 89.2% after 2000 cycles at a current density of 5 A/g. Meanwhile, the as-prepared porous CNF also shows a high CO2 adsorption uptake, 5.08 mmol/g at 0 degrees C and 1 bar. The possible reason and mechanism have been discussed. (C) 2019 Elsevier Ltd. All rights reserved.