A Focus+Context technique based on circle packing is presented for interactive visualization of large hierarchical data. First, a triangular mesh generating method based on externally tangent circles packing is proposed to establish context. Then a method for triangular mesh neighbors tracking is introduced. To realize the context consistency for Focus+Context technique, a layout method for the distorted brother nodes of the focus node is presented based on triangular mesh neighbors tracking, and a recursive method for the children nodes of the focus node is described. Experimental results show that this method can realize fisheye view and can achieve focus and context consistency. The method has been applied to the interactive visualization of file systems, and an interactive visualization tool is introduced.