As the “ageing echo” of the “Baby Boom”, the “Ageing Boom” has not yet received sufficient scholarly attention. Since the founding of the People's Republic of China, the nation has experienced four distinct “Baby Boom” cohorts, which are projected to transform into “Ageing Boom” during the periods 2010-2018, 2022-2036, 2041-2054, and 2071-2079 respectively. Each “Ageing Boom” represents a peak in the growth of the new elderly population, and its cumulative and superimposed effects will drive China's ageing population through phased transformations characterized by sequential stages: ascent, peak, buffer, and decline. China's demographic ageing under the “Ageing Boom” paradigm exhibits both distinctive and general characteristics: a historically unprecedented population scale, asynchronous growth in size and proportion, ageing of the age structure, balancing of the gender structure, and steadily rising survival rates. Focusing on the ongoing second “Ageing Boom”, projections indicate that approximately 330 million individuals will enter old age, with urban residents and population with at least secondary education constituting the majority of this elderly cohort. These demographic shifts present dual implications—harboring developmental opportunities while simultaneously posing practical challenges that require prudent consideration and proactive responses.