The positioning precision of system plays a very important role in ship navigation. As a navigation system, Loran C cannot meet the orientation precision, even not be used in some areas. Based on the principle of hyperbola location, in this paper we propose Loran C/Beidou integrated navigation system. We analyze the effect on the positioning precision of two navigation systems and the simulation of orientation precision is implemented. Additionally, we give the definition of the horizontal dilution of precision (HDOP). Theoretical analysis and extensive experimental data show that by integrating Loran C and Beidou, the orientation precision and usable area of Loran C was improved and the shortage of Beidou position system was covered simultaneity.