A novel two-dimensional（2D） Te Se_2 structure with high stability is predicted based on the first-principles calculations. As a semiconductor, the results disclose that the monolayer Te Se_2 has a wide-band gap of 2.392 e V. Interestingly, the indirect-band structure of the monolayer Te Se_2 transforms into a direct-band structure under the wide biaxial strain（0.02–0.12）. The lower hole effective mass than monolayer black phosphorus portends a high carrier mobility in Te Se_2 sheet. The optical properties and phonon modes of the few-layered Te Se_2 were characterized. The few-layer Te Se_2 shows a strong optical anisotropy. Specially, the calculated results demonstrate that the multilayer Te Se_2 has a wide range of absorption wavelength. Our result reveals that Te Se_2 as a novel 2D crystal possesses great potential applications in nanoscale devices, such as high-speed ultrathin transistors, nanomechanics sensors, acousto-optic deflectors working in the UV-vis red region and optoelectronic devices.
