This paper proposes a method of interactive global illumination rendering with spatial-variant dynamic materials under complex illumination. With the spatial-variant dynamic materials, the materials of the scene can be changed while rendering, and the changes to different parts of an object can be different. The non-linear relationship between materials and out-going radiance prevents users from changing the materials with most of existing interactive global illumination rendering algorithms. If different parts of an object are covered with different materials, the materials take much more complex effects on the out-going radiance. So there is still not an interactive global illumination rendering algorithm allow users to make different changes to different parts of an object. This paper approximates a region with spatial-variant dynamic materials by dividing it into numbers of sub-regions, the material in each sub-region is uniform and consistent. The radiance transferred in the scene may be reflected by different sub-regions successively, and the paper divides the out-going radiance according to different sequences of the reflection sub-regions. This paper also represents all materials with a linear basis, and applied the basis to all sub-regions to get all different distributions of the material basis. This paper precomputes all parts of radiance of all material basis distributions. In rendering process, it uses the materials' coefficients of basis to combine corresponding precomputed data to achieve the global illumination effects with interactive performance.