For ion batteries, the choice of electrode materials is very important. Over the years, it has attracted more and more attention. In this study, we propose a new anode material for the Li-ion batteries which is silicon-doped (Si-doped) blue phosphorene (BP). Using the first-principles calculation method, we study the geometry, adsorption energy, diffusion barrier, mechanical strength, specific capacity and charge transfer of lithium adsorbed on a single-layer Si-doped BP surface. The results show that the diffusion of Li in the armchair and zigzag directions on Si 0·125 P 0.875 is 1.04 and 0.55 eV, while the diffusion in the armchair and zigzag directions on Si 0·25 P 0.75 is 1.00 and 0.64 eV. Similarly, the theoretical specific capacities of the two Si-doped BP are 875 mAhg −1 (Si 0·125 P 0.875 ) and 886 mAhg −1 (Si 0·25 P 0.75 ), which are greater than the pure single-layer BP anode in a Li-ion battery. In addition, during the insertion or diffusion of Li, the structural integrity of Si-doped BP can be well maintained. Therefore, it can be concluded that Si-doped BP is an excellent candidate material for Li-ion battery anodes. • The theoretical specific capacities of the two Si-doped BP are 875 mAhg -1 (Si 0.125 P 0.875 ) and 886 mAhg -1 (Si 0.25 P 0.75 ). • During the insertion or diffusion of Li, the structural integrity of Si-doped BP can be well maintained. • The average voltages of the lithium intercalation in Si 0.125 P 0.875 and Si 0.25 P 0.75 are estimated to be 0.91 V and 0.46 V.