A compact hydrogen plasma gun system was designed and tested. There are two rings of graphite and two rings of Ti hydride between coaxial electrodes. Ti hydride is utilized as a reservoir of hydrogen. The surface flashover is taken advantage to produce plasma. The produced plasma density is 1010cm-3~ 1012cm-3 in a volume of a column with radius 1cm~2cm and length of 60cm~80cm. The plasma existing time is over 400m s. The plasma gun system is simple, light-weight and compact. It is suitable for high power microwave tubes.