Gallium oxide (Ga2O3) has five crystalline polymorphs, i.e. corundum (α-phase), monoclinic (β-phase), spinel (γ-phase), bixbite (δ-phase) and orthorhombic (ε-phase). Among these phases, the monoclinic structured β-Ga2O3 is the most stable form, and is a ultraviolet (UV) transparent semiconductor with a wide band gap of 4.9 eV. It is a promising candidate for applications in UV transparent electrodes, solar-blind photodetectors, gas sensors and optoelectronic devices. In recent years, one-dimensional (1D) nanoscale semiconductor structures, such as nanowires, nanobelts, and nanorods, have attracted considerable attention due to their interesting fundamental properties and potential applications in nanoscale opto-electronic devices.Numerous efforts have been made to fabricate such devices in 1D nanostructures such as nanowires and nanorods. Comparing with the thin film form, the device performance in the 1D form is significantly enhanced as the surface-to-volume ratio increases. In order to realize β-Ga2O3 based nano-optoelectronic devices, it is necessary to obtain controlled-synthesis and the high-quality β-Ga2O3 nanomaterials. According to the present difficulties in synthesizing β-Ga2O3 nanomaterials, in this paper, the grid-like β-Ga2O3 nanowires are prepared on sapphire substrates via electric field assisted chemical vapor deposition method.High-purity metallic Ga (99.99%) is used as Ga vapor source. High-purity Ar gas is used as carrier gas. The flow rate of high-purity Ar carrier gas is controlled at 200 sccm. Then, oxygen reactant gas with a flow rate of 2 sccm enters into the system. The temperature is kept at 900℃ for 20 min. The effect of the external electric voltage on the surface morphology, crystal structure and optical properties of β-Ga2O3 nanowires are investigated. It is found that the external electric voltage has a great influence on the surface morphology of the sample. The orientation of the β-Ga2O3 nanowires grown under the action of an applied electric field begins to improve. Only a grid composed of three different growth directions appears. And with the increase of applied voltage, the distribution of nanowires becomes denser and the length increases significantly. In addition, it is found that the chemical vapor deposition method assisted by this external electric field can significantly improve the crystallization and optical quality of the samples.