The invention relates to a double limiting automatic protector for stable output of a transformer, belongs to the field of power transformation of a small-sized transformer, and aims at solving the problem of low safety of a voltage stabilizing circuit when a power line is overvoltage or undervoltage.A pin 2 of a 555 time base integrated circuit is connected with a capacitor and a rheostat; the rheostat is connected with a capacitor and a diode; a capacitor is connected with an alternative current output end and a normally closed contact; the diode is connected with a capacitor, three resistors, a pin 8 and a light emitting diode; the rheostat is connected with a rheostat; the rheostat is connected with a voltage regulator tube, a capacitor and the alternative current output end; the rheostat is connected with a pin 4, a resistor and a pin 6; a pin 1 is connected with two capacitors; a capacitor is connected with a pin 5, the voltage regulator tube, a light emitting diode and a resistor; the voltage regulator tube is connected with a resistor; a pin 3 is connected with an intermediate relay, a capacitor and a resistor; and the intermediate relay is connected with a resistor, a light emitting diode, a capacitor and a diode.The double limiting automatic protector for stable output of the transformer is simple and practical, greatly protects safety of loads, and is applicable to voltage stable output circuits of transformers.