Let be a mixed graph with vertex set , edge set and arc set . A cycle cover of is a family of cycles of such that each edge/arc of belongs to at least one cycle in . The weight of is . The minimum cycle cover problem is the following: given a strongly connected mixed graph without bridges, find a cycle cover of with weight as small as possible. The Chinese postman problem is: given a strongly connected mixed graph , find a minimum length closed walk using all edges and arcs of . These problems are NP-hard. We show that they can be solved in polynomial time if has bounded tree-width.