The invention discloses a filtering and wave trapping circuit-based voltage following negative ion generator. The voltage following negative ion generator is characterized by mainly comprising a transformer T2, a control chip U3, a triode VT1, a discharge terminal E, a potentiometer R1, a diode D2 and the like, wherein the potentiometer R1 is connected between the b end and the f2 end of a gas sensitive sensor Q in series; and the P electrode of the diode D2 is connected with the control end of the potentiometer R1 while the N electrode of the diode D2 is connected with the base electrode of the triode VT1. Negative ions can be generated automatically according to the concentration of harmful gas in the room, so that high sensitivity is achieved, and indoor air can be purified effectively;meanwhile, the sensitivity can be adjusted according to needs, so that the voltage following negative ion generator can be applicable to different occasions; and the discharge terminal can be controlled stably, thereby generating stable negative ions and purifying indoor air effectively.