The invention discloses a switching value acquisition insulating circuit.The switching value acquisition insulating circuit comprises a reverse protection unit, a current fixing unit, a voltage measurement unit and a photoelectric insulation unit, wherein a switching value signal is input into the reverse protection unit which is connected with the current fixing unit, a circuit is not damaged under the protection of the reverse protection unit after the switching value signal input and the ground are reversely connected, and the current fixing unit fixes the input current of a circuit after meeting a voltage opening condition. The voltage measurement unit is connected with the current fixing unit and controls the threshold voltage so as to reach a voltage signal condition for opening the circuit. The photoelectric insulation unit is connected with the voltage measurement unit and insulates an external input signal and an internal control signal so as to avoid the interference of external input signals and avoid the damage to an inner circuit caused by external fault. The invention can ensure the constancy of the input current in the acquisition process of a switching value input signals, ensures the photoelectric coupler to work reliably and has the advantages of simple circuit calculation, low power and low heating value.