We'v just reseived the results concerning the influence of absorbed water on dielectric properties of silicon dioxide nanoparticle. It is shown in the molecular dynamics simulation that with the use of flexible molecules model the increase of number of water molecules in (SiO2)50cluster up to 40 results in amplification of infrared radiation absorption in a frequency range 0-1000 cm-1. Absorption of water molecules by (SiO2)50cluster strongly changes the form of Rahman spectra smoothing all peaks following the first one. The number of active electrons participating in interaction with infrared radiation is consistently increased with the growth of number of absorbed water molecules by cluster. Water molecules are concentrated next to the cluster surface which is formed by the dense packing of SiO2 structural units.