<正>To measure and calibrate the cyclotron o'r new buncher rf voltage is very important for the beam intensity of the HIRFL. So we must use a good method to calibrate rf voltage for the cyclotron or new buncher. The rf voltage of new buncher NB1 is reached to 180 kV which the conventional electronic instrument can not measure due to the high value of Q (10 000). Any probe can not be inserted in the resonant cavity with the high Q value. So we calibrated the new buncher rf voltage in 2005.