From the 17^th to the 19^th centuries，many Chinese Literati were interested in drawing，publishing，reading，criticizing，copying and even revising the Da Qing Yi Tong Tian Xia Quan Tu map. The map series directly reflected their knowledge，concept，and visions about the maritime China，Qing Empire，and the world，which were produced，transmitted，developed and transited for over 300 years. In these maps，one of the most attractive transition of knowledge was maritime knowledge about South China Sea in the 17^th and 18^th centuries. However，few scholars paid attention to studying the key point of the transition. Wang Ri’ang’s Da Qing Yi Tong Tian Xia Quan Tu drew in the Yongzheng 3rd year（1725）. The paper focuses on Wang Ri’ang’s map，tracing the base map and the original data，especially its maritime knowledge about South China Sea. It shows that the maritime knowledge about South China Sea in Wang Ri’ang’s map derived from the maritime activities by Chinese officers and seafarers in the Coastal Southeast China，and spread into the Literati around the Qing Empire.