Depending on the stress level, the operation of wooden beams under prolonged load is characterized by both linear and nonlinear creep. This has been shown by numerous experimental studies of wood. However, it should be noted that the theoretical description of these processes has been little studied or is extremely rarely presented. It follows that one of the priority directions in the calculations of the elements of wooden structures is the derivation of resolving equations of linear or nonlinear creep for various types of stress-strain state. The Maxwell-Thomson equations are used as relations establishing the relationship between stresses and deformations. The technique was tested by comparing the solution with the calculation of well-known researchers. An example of calculation is given for various boundary conditions for fixing a beam of rectangular cross-section loaded with a uniformly distributed load. The deflection value is determined by the grid method. A program has been developed for calculating in the MATLAB package with the possibility of varying the initial data and displaying a graph of the dependence of displacement, bending moment on time. The comparison of the maximum deflection value with the analytical solution is given. It is noted that the stresses practically do not change during creep. The proposed approach can be applied to the analysis of the stress-strain state and bearing capacity of wooden beams of arbitrary cross-section. There are no restrictions on the boundary conditions and the type of loading, and the material of the beam can be not only wood, but also fiberglass.