Antimony (Sb) has shown great potential as an anode material for rechargeable Lithium ion batteries (LIBs) because of its low price, high specific capacity and moderate working voltage. But it suffers from poor cycling performance due to the large volume expansion during the charge/discharge process. Nano-scale modification is an effective strategy to solve this problem. Herein, the electronic structure modulation, chemical stability, Li adsorption and diffusion properties as well as structural deformation of two-dimensional (2D) monolayer antimonene have been systematically investigated using first-principles calculations based on vdW corrected density functional theory. The calculated results reveal the adsorption energies of Li on antimonene are relatively strong (1.70-1.91 eV), and it exhibits a semiconductor to metal electronic phase transition with significant electrons transfer from Li metal to antimonene upon Li adsorbed. Meanwhile, Li atom shows fast diffusion on antimonene with the energy barrier of 0.20 eV, much lower than that in bulk antimony (1.73 eV). More importantly, antimonene shows relatively small structure deformation upon adsorption of high Li concentrations. The present results suggest that 2D antimonene can be a promising flexible anode material for LIBs with large specific capacity, excellent rate capability and long cycling performance. Our results highlight the nanostructure design of high-performance electrode materials for LIBs.