In this work, the device-to-device variation of ferroelectric FinFETs (Fe-FinFET) is demonstrated experimentally by evaluating the threshold voltage ( ${V}_{\text {TH}}{)}$ variation of the devices with different Hf $_{{0}.{5}}$ Zr{0}.{5}O{2} (HZO) thin films. Distinguished from the cognition that large variation caused by stochastic FE domains, the suppressed ${V}_{\text {TH}}$ variation results of the 3-nm HZO FinFETs than that of general FinFETs with HfO2 gate insulator are demonstrated first. Furthermore, for a larger sweeping gate voltage range ( ${V}_{\mathrm {GS,\mathit {rang}{e}}}{)}$ to ensure FE domain switching, the superior variation characteristics of devices with ultrathin 3-nm HZO film are achieved, regardless of ever-expected severe disturbances induced by ferroelectricity with a higher ${V}_{\mathrm {GS,\mathit {rang}{e}}}$ . A comprehensive analysis in distribution characteristics of ${V}_{\text {TH}}$ unveils an enhanced capacity for variation mitigation in Fe-FinFETs operating at lower voltage, which is demonstrated by a reduction of 28.9% in the standard deviation of ${V}_{\text {TH}}$ for 3-nm HZO FinFETs compared to 4-nm HfO2 FinFETs, specifically at ${V}_{\mathrm {GS,\mathit {rang}{e}}}$ of 0.6 V. To account for the phenomenon, a polarization-induced capacitance enhancement variation compensation theory is proposed coupling with film thickness-dependent FE variation. This work provides the guidelines for mitigating the variation to build reliable large-scale integrated circuits based on FE devices.