Abstract: An intense electron cyclotron resonance ion source for proton linac has been deve-loped. At 30 keV, 100 mA hydrogon beam is extracted from the source, proton ratio is greater than 85% and the beam density of 340 mA/cm 2 is achieved, the rms emittance of the beam is around 0.11π mm·mrad. The source has passed 100 h reliability test.