Canal surfaces are widely used in CAD/CAM and geometric modeling. Canal surfaces are envelopes of a moving sphere with a continuously varying radius, hence are usually presented by the parametric equations of their center loci and radii. However, although a canal surface with rational center curve and rational radius is also proved to be rational, the rational parametrization of the canal surface is quite hard to derive. We present a new approach to represent a canal surface, from which three moving planes that follow the canal surface can be directly written down, without resorting to the rational parametrization of the surface. We shall derive a mu-basis from these three moving planes, and this new mu-basis can easily retrieve the parametric equation and the implicit equation of the canal surfaces.