The average characteristics of wind fields and sea conditions in 2006, 2007, and 2008 and sea conditions on South China Sea (SCS) in winter (January) are analyzed by using the merged data from four satellite altimeters. Both wind force and wave heights were the biggest on the northeastern SCS, the Taiwan strait and the Bashi strait, and the second in the southwestern SCS. According to these characteristics, considering the security and economy, four routes are designed for vessels: (1) the shortest route, from the Malacca strait to the Taiwan strait directly; (2) the route to avoid the gales and high waves on the southwestern SCS and the sea area south of Taiwan; (3) the route bypassing Taiwan from east to avoid the gales on the Taiwan strait; (4) the safest but farthest route. It is obvious from the example of the ship MV H that gales and high waves affect greatly the security of the vessels.