  We present the stochastic model of the galactic cosmic ray (GCR) particles
transport in the heliosphere. Based on the solution of the Parker transport
equation we developed models of the short-time variation of the GCR intensity,
i.e. the Forbush decrease (Fd) and the 27-day variation of the GCR intensity.
Parker transport equation being the Fokker-Planck type equation delineates
non-stationary transport of charged particles in the turbulent medium. The
presented approach of the numerical solution is grounded on solving of the set
of equivalent stochastic differential equations (SDEs). We demonstrate the
method of deriving from Parker transport equation the corresponding SDEs in the
heliocentric spherical coordinate system for the backward approach. Features
indicative the preeminence of the backward approach over the forward is
stressed. We compare the outcomes of the stochastic model of the Fd and 27-day
variation of the GCR intensity with our former models established by the finite
difference method. Both models are in an agreement with the experimental data.
