For different definitions of the distribution function,there are different forms of Fokker-Planck equation to describe the energetic charged particles transport in plasma.The different forms of Fokker-Planck eqation have been compared and evaluated from the viewpoint of numerical calculation,and it is indicated that the Fokker-Planck collision term can be interpreted as the convection diffusion term in the velocity space.Based upon this,a code,CAPT,has been made to solve the two-dimensional (space and velocity) time-dependent Fokker-Planck equation by difference method,and it is applied to study the alpha particles transport problem.The loss of alpha particles has been calculated for a typical Tokamak D-T fusion reactor,and the core alpha particles distribution and the lost alpha particles velocity distribution have also been shown.