The work is purposed to the design of diode electron gun for powerful technologic electron linac and to experimental investigations of the beam parameters at the gun exit. The gun feature is the quick cathode replacement. This is very impotent for operating of the accelerator. The gun optics and beam parameters were calculated using the EGUN code. Beam parameters were investigated as at the special test stand so as a component of the linac injector. The gun produces the beam current of 2 A at the anode voltage 25 kV. Measured beam parameters correspond to calculated results.