In multiprocessor system, the topology of interconnection network is critical so that the parallel processing system can efficiently perform various application algorithms in engineering and scientific. An interconnection network is usually represented by an undirected graph G = (V, E), where the node set represents the processors, and the edge set represents the communication link. Petersen-Gaussian (PG) networks are a broad family of interconnection networks for multi processor systems proposed recently. In this paper, a special case of PG networks, called Petersen-Twisted-Torus (PTT) network, is considered. The authors analyze the diameter of PTT network, and find that PTT has smaller diameter and lower costing requirement than the well-known honeycomb mesh, diagonal mesh, torus, hexagonal torus, honeycomb torus and Petersen torus networks.