<p>The influence of the silicon atom of the Be_<i>n</i>+1H₂O cluster is investigated by the first principles calculation method based on density functional theory. The results are as follows: the water molecule tends to adsorb on the outer surface of Be_<i>n</i>Si cluster in parallel, and the structure of the cluster changes strikingly after adsorption. The H–O bonds in the water molecule are extended or even broken, and the reactivity of H₂O significantly increases. After silicon atom doping, the adsorption energy of the cluster is 5.3–10.9&#xa0;eV, which is noticeably higher than that of the Be_<i>n</i>H₂O cluster (3.7–5.4&#xa0;eV), and the average binding energy and HOMO–LUMO GAP (HLG) of the cluster also increase. Frontier orbital and state density analysis manifested that the hybridization rate of Be_<i>n</i>Si cluster with the water molecular orbitals is higher than that of Be_<i>n</i>+1 cluster. In contrast, the orbital hybridization within water molecules is reduced. This results in an enhanced interaction between the cluster and the water molecule, but reduces the H–O bond in the water molecule. This causes the water molecule to dissociate. Our study proclaims that the doping of the silicon atom facilitates the interaction between the beryllium cluster and the water molecule, and enhances the reactivity of the water molecule at the same time. The adsorption of the water molecule on Be_<i>n</i>Si cluster is typical dissociative adsorption.&#xa0;</p>