Partitioning a given complex 3D mesh model into some meaningful subparts is one of the fundamental problems in digital geometry processing. In this paper, we present an algorithm for decomposing an object represented in triangle meshes into components consistently. The segmentation is based on two key ideas. First, it exploits the discrete protrusion function on triangle mesh, and then it adopt minimal cut on the dual graph of original mesh. The experiments show that it is effective and powerful in decomposing a 3D mesh into its significant components, and is invariant to deformations, and numerically robust to noise.