The invention discloses a safety early warning circuit for a power distribution operation site. A field intensity over-limit early warning circuit uses a high-voltage trigger circuit to determine whether to reach 80% of an over-limit threshold according to the electric field intensity detected by an electric field sensor; if so, a controllable amplifying circuit carries out amplification, whereinthe amplification factor is controlled by the amplitude of the electric field intensity change calculated by an integrating circuit; a human body induction current calculation circuit works; a division operation circuit carries out a division operation on the electric field intensity and the human body impedance and an induction current acting on a human body is calculated; a safety alarm triggercircuit uses the received induction current as the power supply of the controllable trigger circuit and the change amplitude of the electric field intensity controls an conduction angle of an unijunction transistor T1, so that conduction is triggered when the current is in an over-limit state, a triode Q1 is driven to be in conduction and an electrolytic capacitor E1 is charged through a resistorR24; and acousto-optic safety distance early warning is carried out under the condition that the current exceeds the limit and the allowable duration exceeds an electric shock safety range. Therefore,the accuracy of the safety early warning distance can be effectively improved.