A thorough investigation of the oxidation mechanism of sp(2)-sp(3) hybrid carbon materials is helpful for the morphological trimming of graphene. Here, porous graphene (PGN) was obtained-via a free radical oxidation process. We further demonstrated the difference between traditional and free radical oxidation processes in sp(2)-sp(3) hybrid carbon materials. The sp(3) part of graphene oxide was oxidized first, and well-crystallized sp(2) domains were reserved, which is different from the oxidation mechanism in a traditional approach. The obtained PGN shows excellent performance in the design of PGN-based detectable molecule separation or other biomedical applications.