Abstract: Plural electrical property of coal was measured under frequency signal excitation. The results show that amplitude spectrum and phase spectrum of different kinds of coal respectively present different characteristics. In the test frequency range of 0.1 Hz to 100 kHz, Z-f curves of coals all show monotone decrease. The amplitude-frequency curves of different types of coal and rocks differ from one another, and inflection point positions are also different. Phase frequency curves of different coal and rocks present different characteristics. Phase is generally negative. Coal and rocks overall show the property of capacitive reactance. Curve shapes and extreme value point positions are respectively different. The amplitude frequency and phase frequency characteristics of coal and rocks were first analyzed. According to the differences of impedance and phase of coal in different metamorphic extent under the same electrical frequency domain, electricity exploration is used to prospect its compositions and structures, which provides theoretical and experimental basis for electric prospecting.