In recent years, n-type In2O3 nanowires (NWs) have attracted tremendous attention for their excellent optical and electrical properties. Field-effect transistors (FETs) based on n-type In2O3 NWs have been widely applied to memory devices, solar cell, especially photodetector for UV region. However, the relatively low electron mobility of the In2O3 NWs grown by chemical vapor deposition (CVD) limits their further application. Here, by doping Ga, NWs with diameter down to 30nm diameter grown by chemical vapor deposition (CVD) in ambient pressure are successfully prepared. The Ga doping is found to enhance the crystal quality of In2O3 NWs and helps to yield thin and uniform NWs with low oxygen vacancy concentration. Comparing to the device based on pure In2O3 NWs grown in the same condition, the threshold voltages of field effect transistor based on 10 at% Ga doped In2O3 NWs shift in positive gate voltage and the corresponding carrier concentration at zero gate voltage decrease from ~1.29*1019 cm-3 to 1.15*1019 cm-3. Moreover, affected by the control of radial growth and reduction of oxygen vacancies that can act as ionized impurity scattering centers, FET based on single 10 at% Ga doped In2O3 NWs with diameter of about 30 nm with electron mobility up to ∼750 cm2V-1s-1 can be achieved. Meanwhile, the mobility of corresponding parallel NWs array FET is up to ∼210 cm2V-1s-1. All these results indicate promising potency of Ga doped In2O3 NWs in low-cost and large scale fabrication for high performance electronics.