The invention provides an annular capacitive voltage divider for the linearity calibration of an impact voltage divider. The capacitive voltage divider comprises a conductive shell, a guide rod, a low-voltage arm and a data acquisition device; the guide rod passes through the shell; the guide rod is in insulation connection with the shell at a position where the guide rod passes through the shell; the first end of the guide rod is used for connecting an impulse voltage generator, and the second end of the guide rod is used for connecting a voltage divider; the low-voltage arm is arranged in the shell; the low-voltage arm comprises a capacitor body; the first end of the capacitor body is electrically connected with the shell, and the second end of the capacitor body is electrically connected with the guide rod; the first input end of the data acquisition device is electrically connected with the first end of the capacitor body, and the second input end of the data acquisition device is electrically connected with the second end of the capacitor body; and the data acquisition device is used for acquiring the voltage of the capacitor body. The capacitive voltage divider provided by the invention is of a pure capacitive structure and is free of inductance; and the guide rod is adopted to replace a high-voltage lead, so that the capacitive voltage divider has a strong anti-interference ability, so that the measurement of the linearity of the impulse voltage divider can be more accurate.