"Complementary monetisation"is a new subject under the background of contemporary digital economy.Complementary money has a long history,but only recently has it gained people s attention and a special study of it started a few decades ago.It is only in recent years that the study of complementary money has been established as a discipline.As a subject,"complementary monetisation"has gone through four periods when the concept was put forward(1891-2012),when the concept was established(2013-2019),when the discipline was initially established(2020-2023),and when the discipline has been developed(2023-present).This paper summarizes the research results of complementary money at home and abroad over the years,trying to show the historical context,formation process,development trend and strong vitality of the new discipline of"complementary money".