Objectives: Smoking prevalence has significantly increased among Chinese adolescences in the past decades. The aim of our study is to investigate the trends and changing patterns in age of smoking initiation among the Chinese population. Study design: Pooled data from the 2006-2015 China Health and Nutrition Survey was used for analysis. A total of 10,032 adults aged >= 18 years who were born between 1950 and 1997 were separated into five birth cohorts (1950-1959, 1960-1969, 1970-1979, 1980-1989 and 1990-1997). Methods: Age-specific (10-24 years) smoking initiation rates were calculated by gender, educational level and urbanisation. The multiple logistic models were used for estimates of changes in smoking initiation age. Results: The mean age of smoking initiation decreased substantially from 22.0 years (95% confidence interval [CI]: 21.2-22.7) to 17.5 years (95% CI: 16.2-19.1) over five generations. A large decrease was seen in the initiation age group of 15-24 years in the 1980s cohort (15-19 years: odds ratio [OR] = 0.57; 95% CI: 0.19-0.97; 20e24 years: OR = 0.45; 95% CI: 0.18-0.82); a significant decrease was also found in the 1990s cohort (15-19 years: OR 1/4 0.47; 95% CI: 0.11-0.94; 20-24 years old: OR = 0.34; 95% CI: 0.14 -0.85). The peak age of smoking initiation changed from 20 years old to 18 years old over the five generations. Conclusions: The age of smoking initiation has decreased rapidly in the Chinese population in the past decades. Chinese adolescents are becoming the main target group for the tobacco marketing industry, and national legislations are urgently required. (c) 2020 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.