Wave overtopping risk was analyzed to get an overtopping probability of coastal levees in Shanghai. With representative structure of coastal levees, the overtopping probability of each coastal levee was calculated by Monte Carlo method. The results showed that the overtopping risk of up-to-date coastal levees is less, but one of Chongming area rather large. The overtopping sensitive analysis of each character parameter demonstrated that the parameter variation of high tidal level is the major factor of overtopping occurrence, and the proper rise in free board of coastal levee is a key to prevent overtopping risk.