In October 2013, China signed the Minamata Convention on Mercury as the 30th signatory state, and its implementation will have a significant impact on the development, use, and management of mercury. Therefore, estimating excess mercury has become extremely important for providing fundamental information for strategic mercury management, such as planning the necessary storage capacity and the timeline for taking appropriate actions. In this study, quantitative information on past and current domestic supply and demand and on excess mercury over a 55-year period (1996–2050) in China was assessed through maximum and minimum scenario analyses. The total mercury supply increased markedly between 1996 and 2016, particularly during the 3 most recent years. The total demand for mercury during the same period increased gradually compared to the total supply. The amount of annual excess mercury has grown rapidly since 2014, from 636 –756 tons in 2013 to 2725–2845 tons in 2016. The minimum excess mercury scenario shows that cumulative excess mercury will continue to decline from 2017 on, and will reach one-third of 2016 levels in 2050. The cumulative amount in 2050 in the maximum scenario will be 3.5 times higher than that in the minimum scenario. The method applied would be useful for policymakers in other countries that are facing similar problems.