A new discharge system which can generate stable atmospheric pressure DC glow discharge is reported in this paper. The system is made up of an inner line electrode and an outer cylinder-like electrode. The radii of the inner and outer electrodes are only 0.08 and 2 mm, respectively. The transition from corona discharge to glow discharge is observed. The experiments show that the discharge has typical features of normal glow discharge and can produce nonthermal plasma. It has been used as an ambient ion source, and chemicals such as formic acid, acetic acid, phenol, and benzoic acid can be ionized well.