Abstract: The traditional approach of treating kinetic problem of plasma is solving kinetic equation for f (v, r,t), then calculating the wanted macroscopic quantities by integration. It is shown that this is not a convenient and direct way. If transforming f (v, r, t) in to the Fourier space K, with respect to v, getting f(K, r, t) and corresponding equation of it, then only the value of f (K, r, f) near K≈0 is need for practical interest Two examples, one is the derivation of dispersion equations of electro-magnetic modes in a inhomogenius low β plasma, the other is the effect of collision on the temperal echo, show the main procedures of this approach and its advantage over the traditional one.