The fast arcing protection of the electron cyclotron resonance heating(ECRH)is very important in the heating experiment of the HL-2A tokamak.ECRH has the ability of 1MW using two gyrotrons (each about 500kW).The states of the protected objects must been detect then deal with effectively arcing-events in order to accomplish the protection function.The fast arcing protection includes two parts such as some arcing detectors and one arcing protector for the one gyrotron and one waveguide line.The ECRH arcing protection system must be fast enough and very reliable,and the total response time is less than 25μs.