Summary: By introducing the concepts of stably dissipative matrices and graphs, some conditions for stably dissipative matrices are given. On this basis, graph theory is used to classify all stably dissipative 3D Lotka-Volterra systems, and five classes of maximal stable dissipative graphs are obtained for these systems. Finally, necessary and sufficient conditions of being stably dissipative for every class are studied, under which the matrices associated with the graphs are stably dissipative.