The invention discloses a positive and negative voltage generating circuit, which is connected with an external power supply and a load circuit. The positive and negative voltage generating circuit iscomposed of at least two groups of structural units connected in series in the same direction, and can output a plurality of groups of positive and negative power supplies. Wherein, the structure unit is composed of a voltage limiter and a capacitor in parallel; The negative electrode of the voltage limiter in the first group of structural units is connected with the positive electrode of the external power supply, and the positive electrode of the voltage limiter in the last group of structural units is connected with the negative electrode of the external power supply. The ground signal ofthe load circuit is connected with the capacitor zero potential terminal, the capacitor zero potential terminal is the connection terminal between any adjacent capacitors, and the capacitor terminalsconnected with the load circuit other than the capacitor zero potential terminal are the capacitor potential terminals; The negative electrode of the external power supply is not common to the zero potential terminal of the capacitor. The invention uses the passive device with small power to build, reduces the cost, saves the size, has a wider application range, is simple to realize, and has veryhigh reliability.