Abstract: The status of operating and maintaining for EN tandem accelerator at Peking University between 2006 and 2007 was introduced. It includes the conditions for the accelerator running stability with higher terminal voltage, the effect of gas stripper recirculation assembly on the beam species and the transmission of ion beams. It has been demonstrated that the character of voltage divider resistances and the humidity of insulating gases are two very important factors to the accelerator running stability, and the gas stripper recirculation assembly makes the ions of medium and high electronic state increasing much more, at the same time, improves the transmission of ion beams. The primary experimental study on the measurement of weak beam current shows that the PIN detector can be used to measure the beam less than 0.01 nA.