The improvement in the grid-controlled electron gun of the 200MeV linac in the National Synchrotron Radiation Laboratory (NSRL) was discussed. The s and us mode pulser systems were put together

so it was not necessary to change circuit board when work mode was alternated. After the bench tests of the pulser on both p s mode and us mode were done

and some relations between current and grid voltage

filament current

anode voltage

were obtained the combined pulser was installed in the LINAC of HLS (Heifei Synchrotron Radiation Light Sourc).