The invention discloses an integrated three-phase all-fiber optical current transformer and solves a technical problem of how to improve all-temperature measurement precision and integration reliability. The integrated three-phase all-fiber optical current transformer comprises a light path system unit and a digital signal processing unit, wherein a light source, a polarization-maintaining coupler, a polarizer, a straight waveguide, a delay fiber and a sensing ring of the light path system unit are sequentially connected, the digital signal processing unit is provided with a light source intensity noise inhibition unit, a signal processing unit, a phase demodulator and a phase driving circuit which are sequentially connected, and the phase driving circuit is connected with the straight waveguide. Compared with the prior art, intensity noise is inhibited through a dual-polarized light path, all-temperature measurement precision and small current measurement precision of the current transformer are improved, a time division multiplexing circuit is employed by the signal processing unit, optical devices and the sensing ring of the light path system are simplified, phase time delay of the sensing ring is precisely controlled, automatic light path compensation is realized, curing manufacturing of the sensing ring is realized, and all-temperature measurement precision and reliability of the all-fiber optical current transformer are improved.