[en] Highlights: • The FPL method is applied for the first time on the BACE1-inhibitor complex. • Interaction energy is an appropriate criterion to rank affinity of BACE1 inhibitor. • The obtained results have strong correlation with experimental data ($R=0.92$). • The computed error is relatively small ($\delta E=7\%$). • The van der Waals contributes ∼56% to total interaction energy. The fast pulling of ligand (FPL) method, which evaluates the relative ligand-protein binding affinity with low CPU usage and high accuracy, was applied for the first time to determine the affinity of β-secretase 1 (BACE1) and its inhibitors using steered-molecular dynamics simulations. The total non-bonded interaction energy difference $\mathrm{\Delta }{E}_{\mathit{total}}$ is a highly appropriate criterion to predict the relative BACE1-inhibitor binding affinity with strong correlation to experimental data ($R=0.92$) and small deviation ($\delta E_{\mathit{total}}=7\%$). The van der Waals interaction and electrostatic interaction contribute 56% and 44% to the total non-bonded interaction energy between BACE1 and its inhibitors.