This paper focuses on V-I characteristic of the carbon fiber membrane collecting under the four corona electrode which are square oblique second tooth white prick line, prick plate 20mm tooth long, prick plate 30mm tooth long and 40mm. Respectively research voltage characteristic of dry film collecting and wet film collecting, the comparison of dry film collecting and metal plate in the same condition. The result is that carbon fiber membrane can completely replace metal plate collecting pole, the more storage of collecting membrane, the higher corona current, it is benefit for collecting. Wet film relative to the dry film, provides a higher voltage spark discharge, in order to maintain higher electric field strength, which is very beneficial for collecting.