Background <p>The EQ-5D-Y-3L and value sets have been developed in mainland China. However, a nationally representative EQ-5D-Y-3L population norm for children has not yet been established. This study aims to develop EQ-5D-Y-3L norms for children in mainland China based on a national survey.</p> Methods <p>The data for this study were derived from the Medication Literacy Investigation of Chinese Children (MLICC). The survey spanned 18 geographically and socioeconomically diverse provinces/regions in mainland China, employing a multi-stage quota sampling strategy stratified by gender and age. Child participants (8–18 years) completed the survey through an online platform, while guardians provided household information. The survey was supervised by trained investigators through one-on-one, face-to-face interviews, yielding a final sample of 5,191 participants for analysis. The utility index (UI) was reported for the entire sample (weighted using 2020 census data) and by the characteristics of the study participants.</p> Results <p>The weighted mean UI score was 0.951 (SD = 0.099). The most frequently reported problem was feeling worried, sad or unhappy (WSU) (24.59%), followed by having pain or discomfort (PD) (17.87%), doing usual activities (UA) (7.73%), and mobility (MO) (4.76%), with looking after myself (LAM) being the least reported problem (4.23%). Respondents who were male, younger, and those with better behaviours, no chronic conditions, better family functioning, and residence in a relatively economically developed region had higher UI scores (<i>p</i> &lt; 0.001).</p> Conclusions <p>This study provides national EQ-5D-Y-3L population norms for children in mainland China. The study found that children in mainland China have relatively higher UI scores compared with those in other countries. A wide range of socioeconomic and behavioral factors are associated with the UI scores.</p> Trial registration <p>Clinical trial number was not applicable.</p>