The case when the interplanetary stochastic magnetic field is modeled as a spatially inhomogeneous scattering medium with the diffusion coefficient proportional to distance to the Sun. Galactic cosmic ray (CR) propagation problem in a medium of this sort is solved by the iteration method. The iteration solution is compared with exact analytical solution for inhomogeneous medium and also with iteration solutions to describe the different CR propagation effects in heliosphere when the scattering parameters depend on the particle energy. It is demonstrated that two iterations are sufficient to describe CR intensity. It is shown that CR intensity near the Sun is significantly smaller for this model than for the model with CR diffusion coefficient constant in space.