In this paper, we present a new direct methed for solving the problem of a mult ilayer dieleotrio planar waveguide. Applying this method to a non-uniform dieleotrio planar waveguide, we can solve the problems of an arbitarily graded planar waveguide for either TE or TM modes. Taking parabolic and exponential refractive index profiles as two examples, we have shown that high accuracy can be abtained by using this methed provided that the waveguide can be divided into proper number and thickness of layers.