Eu-doped GaOOH nanoparticles with size of 5-8 nm were prepared by hydrothermal method using sodium dodecylbenzene sulfonate (SDBS) as surfactant. Eu-doped α-Ga2O3 and β-Ga2O3 were further fabricated by annealing GaOOH-Eu and then characterized by X-ray diffraction(XRD), transmission electron microscopy (TEM) and photoluminescence (PL). The TEM results show that monodisperse Eu3+-doped GaOOH nanoparticles form and then transform into Eu3+-doped α-Ga2O3 and β-Ga2O3 through annealing the GaOOH-Eu nanoparticles at 600 and 900 °C, respectively. PL studies indicate that GaOOH-Eu has the highest intensity at 618 nm. Luminescence quenching is observed at higher Eu3+concentration in all samples.