Based on field geological survey, petrogeochemical analysis and ¹⁴C dating by high precision accelerator mass spectrometry, the Cenozoic volcanism in the Mock River region of central Greater Hinggan Mountains was studied. It’s proved that there happened active volcanisms in the Cenozoic period in Mock River region, which covered over 80 km² area and erupted in the strombolian style. Integrated data of those in adjacent regions, some conclusions can be drawn as followings. Firstly, the Cenozoic volcanic rock in this area belongs to the OIB basalt derived from the reactivating deep fault under the extensional tectonic environment. Secondly, little or no crust-derived material was contaminated during the magma ascending.