Objective To assess the current prevalence of and risk factors for infertility among couples of reproductive age in China. Design Population‐based cross‐sectional study. Setting We approached 25 270 couples in eight provinces/municipalities, of whom 18 571 (response rate 74%) were interviewed. Population Couples living together and married for more than 1 year, of whom the female spouse was 20–49 years old. Methods Women were approached via telephone and face‐to‐face conversation to complete the standardised and structured questionnaire by trained interviewers. Main outcome measures Prevalence of and risk factors for infertility. Results Among women ‘at risk’ of pregnancy, the prevalence of infertility was 15.5% (2680/17 275). Among 10 742 women attempting to become pregnant, the prevalence of infertility was 25.0% (2680/10 742), which increased with age in the second population. Among women who failed to achieve pregnancy in the last 12 months, 3470 finished our questionnaire about fertility care, and 55.2% (1915/3470) of them had sought medical help. Sociodemographic risk factors for infertility included lower educational level adjusted odds ratio (aOR) 3.4, 95% CI 2.0–5.5 and employment (aOR 2.3, 95% CI 1.9–2.9). Clinical risk factors were irregular menstrual cycle (aOR 1.8, 95% CI 1.2–2.5), light menstrual blood volume (aOR 1.6, 95% CI 1.2–2.0), history of cervicitis (aOR 1.5, 95% CI 1.2–2.0) and endometriosis (aOR 3.1, 95% CI 1.1–9.3), previous stillbirth (aOR 2.1, 95% CI 1.3–3.3) and miscarriage (aOR 2.7, 95% CI 2.1–3.5). In addition, history of operation was a significant risk factor of infertility. Conclusions Among couples of reproductive age in China, the prevalence of infertility was 25%, and almost half of the couples experiencing infertility had not sought medical help. Tweetable In China, 25% of couples actively attempting to become pregnant suffered infertility. Tweetable In China, 25% of couples actively attempting to become pregnant suffered infertility.