Carbon nanofibers decorated with porous carbon nanotubes were prepared by electrospinning and annealing methods. The microwave reflection loss of the products was investigated in the frequency range of 2-18 GHz. The bandwidth with a reflection loss less than -10 dB covers a wide frequency, ranging from 7.0 to 14.1 GHz with thickness of 3.0-5.5 mm, and the minimum reflection loss is -44.5 dB at 10.7 GHz with thickness of 2.0 mm. The large reflection loss and wide reflection band reveal that the products could be a promising candidate for microwave absorption.