Atmospheric pressure plasma jets based on dielectric barrier discharge have found many applications, yet its basic behavior and its formation mechanism are poorly understood. We carried out some basic experimental studies on this problem. Unlike the other similar studies based on ICCD, two MPTs with aligned slits, digital camera, and electrical measurements were mainly used to investigate the plasma jet’s behavior under different discharge conditions. Despite the materials employed in our experiment are quit simple, by comparing the measuremental results, a new charge-overflow phenomenon is obsewed, and the plasma jet mechanism (e.g. how the plasma jet is formed, how is it transported, what are the main parameters that determines the jet length, etc.) are discussed based on the experimental results.