The invention relates to an electric demonstrating device for gradual luminescence display, belonging to the teaching apparatus demonstration field. The electric demonstrating device consists of a test hole, an oscillatory type amplification unit, a loop pulse unit, a four-door type electronic switch, a display pre-unit, a display system and a voice grade. The test hole is connected with a tested element, after going through the element, the voltage of the loop pulse unit can be lowered to some extent, after amplified and adjusted by the oscillatory type amplification unit, the display pre-unit can be reliably started to excite the display system and the voice grade to form prompt of sound and light, and the display system is provided with a display driver stage, a display level, a power amplifier stage and a display oscillator stage to form a common cathode luminescent tube in the display stage, which is capable of giving out different rays of light. The electric demonstrating device has certain interestingness, can be used for training a large number of teenagers to love science, and plays an active part in improving the basic quality of students.