In this work, we perform first-principles study to investigate the potential of two-dimensional (2D) SiS as an anode material for lithium-based batteries. Four predicted structures of 2D SiS are considered, including α-SiS, β-SiS, Pma2-SiS and silicene sulfide. Results show that among the samples studied, α-SiS exhibits: i) a negative adsorption energy to lithium of −0.44 eV; ii) the highest theoretical specific capacity of 446 mAh g−1, which is even higher than that of phosphorene (433 mAh g−1) and Ti3C2 (320 mAh g−1); iii) a low average open-circuit-voltage (OCV) of 0.20 V; iv) a fast lithium diffusivity with an energy barrier of only 0.17 eV, lower than that on MoS2 (0.25 eV), VS2 (0.22 eV) and silicene (0.23 eV); and v) a change from semiconducting to metallic state after lithiation. These advantages demonstrate that α-SiS is a promising anode material for lithium-ion batteries, and gives a choice for other lithium-based batteries such as lithium-oxygen and lithium-sulfur batteries as well.