Background  The next influenza pandemic will create a surge in demand for health resources in China, with its current population of >1·3 billion persons and under‐developed medical care and public health system. However, few pandemic impact data are available for China.

Objectives  We estimated the effects of a future influenza pandemic in China by examining pandemic scenarios of varying severity and described the time distribution of cases during a first wave.

Methods  We used a Monte‐Carlo simulation model and death rates, hospitalizations and outpatient visits for 1918‐ and 1968‐like pandemic scenarios and data from the literature or experts’ opinion to estimate four health outcomes: deaths, hospitalizations, outpatient medical visits and clinical illness for which medical care was not sought. For each of the two scenarios we estimated outcomes by week using a normal distribution.

Results  We estimated that a 1968 scenario in China would result in 460 000–700 000 deaths, 1·94–2·27 million hospitalizations, 111–117 million outpatient visits and 192–197 million illnesses for which medical care was not sought. Fifty‐two percent of hospitalizations occurred during the two‐peak weeks of the first wave. We estimated that patients at high‐risk of influenza complications (10–17% of the population) would account for 61–75% of all deaths. For a 1918 scenario, we estimated that 4·95–6·95 million deaths, 20·8–22·7 million hospitalizations and 101–108 million outpatient visits could occur.

Conclusion  Even a 1968 pandemic scenario will pose substantial challenges for the medical and public health system in China, and planning to manage these challenges is essential.