Abstract: Two D-dot voltage monitors and a B-dot current monitor have been designed for laser-triggered switch of PTS prototype. The D-dot monitor consists of a capacitive divider where the capacitance to ground in the probe is relatively small and does not affect the calibration. One has been installed in the switch entrance and the other in the export. The waveform of the D-dot in export is different from the calculated waveform because the capacitance to the high-voltage electrode of export is small and almost equal to the capacitance to the electrode of entrance, so the monitor influences the voltage in the export and that in the entrance. The coupling coefficient from the monitor to the high-voltage electrode of entrance can be obtained by test, then the modified waveform is calculated. The B-d