An invasive method has been developed for a measurement of voltage response of acupuncture points themselves at different frequencies from 10 to 80Hz. The input voltage for each frequency varied from 100 mV to 1000 mV or 200 mV to 1000 mV. The output voltage response to input voltage has a linearity property under the same frequency, and the output voltage response to input voltage exhibit non-linearity under different frequencies. A simple model is developed to explain the unique characters of acupuncture points that the acupuncture points are a resistor-and-capacitor combined system.