<p>Parental perception of their child’s weight may influence their feeding practices. However, few studies examined the longitudinal associations and the potential sex differences within it. Considering that parents may perceive and respond differently to boys’ and girls’ weight status due to biological and sociocultural expectations, it is important to investigate potential sex differences. The prospective cohort study aims to examine the associations between parental weight perception and their non-responsive feeding practices in preschool children and explore child sex differences in the association. Parent–child dyads (<i>n</i> = 426, M_age = 3.76, SD = 0.50, 53.6%boys) were surveyed at two time points separated by a 2-year interval in China. Generalized estimating equations (GEE) were conducted to examine longitudinal associations between parental weight perception and non-responsive feeding practices (restrictive feeding, food as a reward, and pressure to eat), adjusting for key confounders, including child age, body mass index-for-age z-score (BAZ), having siblings, primary caregiver identity, and grandparent-parent parenting. Sex-stratified analyses were conducted to examine whether the associations differed between boys and girls. Parental underweight perception was associated with restrictive feeding (<i>B</i> =  − 0.260, <i>p</i> = 0.004) and pressure to eat (<i>B</i> = 0.350, <i>p</i> &lt; 0.001), but not with food as rewards (<i>B</i> = 0.015, <i>p</i> = 0.868) in the overall sample. However, parental overweight and obesity (OWOB) perception was not associated with restrictive feeding (<i>B</i> =  − 0.029, <i>p</i> = 0.819), food as a reward (<i>B</i> =  − 0.228, <i>p</i> = 0.146), and pressure to eat (<i>B</i> =  − 0.284, <i>p</i> = 0.054). Among boys, underweight perception was associated with restrictive feeding (<i>B</i> =  − 0.205, <i>p</i> = 0.023) and pressure to eat (<i>B</i> = 0.362, <i>p</i> &lt; 0.001); OWOB perception was associated with pressure to eat (<i>B</i> =  − 0.325, <i>p</i> = 0.024). While no significant associations were observed among girls for restrictive feeding, food as a reward, and pressure to eat.</p><p><i>Conclusion</i>: Findings in this study suggested that the longitudinal associations between parental weight perception and feeding practices differed by sex among Chinese preschool children. Healthcare providers should consider offering anticipatory guidance to parents who perceive their child’s weight as abnormal, educating them on evidence-based, sex-specific strategies to promote healthy feeding practices.<Table Float="No" ID="Taba"> <tgroup cols="2"> <colspec align="left" colname="c1" colnum="1" /> <colspec align="left" colname="c2" colnum="2" /> <tbody> <row> <entry nameend="c2" namest="c1"> <p><b>What is Known:</b></p> <p><i>• Cross-sectional studies suggest that parental weight perception is associated with non-responsive feeding practices and that these associations may differ by child sex.</i></p> <p><i>• In China, cultural beliefs such as “a chubby child is a healthy child” may lead parents to underestimate their child’s weight, potentially influencing their feeding behaviors.</i></p> <p><b>What is New:</b></p> <p><i>• This longitudinal study in urban Chinese preschoolers found that parental underweight perception was associated with increased pressure to eat and reduced restrictive feeding over time.</i></p> <p><i>• These associations were observed only among boys, highlighting potential sex-specific mechanisms shaped by cultural norms as early as the preschool years.</i></p> </entry> </row> </tbody> </tgroup> </Table></p>