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The classification of topological states of matter depends on spatial dimension and symmetry class. For non-interacting topological insulators and superconductors, the topological classification is obtained systematically and non-trivial topological insulators are classified by either integer or Z _2 . The classification of interacting topological states of matter is much more complicated and only special cases are understood. In this paper we study a new class of topological superconductors in (2 + 1) dimensions which has time-reversal symmetry and a $\mathbb {Z}_2$ spin conservation symmetry. We demonstrate that the superconductors in this class are classified by $\mathbb {Z}_8$ when electron interaction is considered, while the classification is $\mathbb {Z}$ without interaction.