The problem of determining of stress state in beams with sinusoidal perforation under concentrated force was considered. An empirical expression has been obtained for the stress distribution in dependence on parameters of perforation and force factors – bending moment and shear force. Von Mises equivalent stresses near the edge of openings is presented by the sum of two items caused by two types of deformations – shear and bending. The numerical coefficients of this dependence were determined with help of the finite element method calculations. The obtained empirical relation was verified by FEM calculations using the ANSYS software. It was studied effect of the fillet radius in corners of openings on stress state of beams with sinusoidal perforation in wide range of relative height of openings. Obtained results allow to conclude that calculation of equivalent stresses in beams with sinusoidal perforation bring to divergence not exceeding 5%.