This study explored the association between parental discipline and mental health in a sample of 21,366 Chinese preschool children (mean age = 4.82 ± 0.89 years; 51.77% boys, 48.23% girls). Parenting practices were measured as overall parenting scores, laxness, overreactivity, and verbosity, and children's mental health was assessed by the official simplified Chinese version of the Strengths and Difficulties Questionnaire (SDQ). Both outcomes were dichotomized using validated cut-offs for Chinese preschoolers, and odds ratios are reported as the odds of meeting these cut-off definitions (Total Difficulties Score > 14; adequate Prosocial Behavior Score ≥ 6). The results indicated that higher parenting scores (for total difficulties: AOR = 4.03; 95% CI: 3.64-4.46; for prosocial behavior: AOR = 0.48; 95% CI: 0.45-0.51), particularly in laxness (for total difficulties: AOR = 1.28; 95% CI: 1.23-1.34; for prosocial behavior: AOR = 0.88; 95% CI: 0.85-0.91) and overreactivity (for total difficulties: AOR = 1.83; 95% CI: 1.76-1.90; for prosocial behavior: AOR = 0.66; 95% CI: 0.64-0.68), were associated with higher odds of a Total Difficulties Score > 14 (i.e., risk of mental health difficulties) and lower odds of an adequate Prosocial Behavior Score (≥ 6), while verbosity (for total difficulties: AOR = 0.80; 95% CI: 0.77-0.84; for prosocial behavior: AOR = 1.23; 95% CI: 1.19-1.27) was associated with lower odds of a Total Difficulties Score > 14 and higher odds of an adequate Prosocial Behavior Score (≥ 6). Subgroup analyses suggested potential effect modification by education level and child age, but most interaction effects were not significant after multiple comparison correction. The findings emphasize the need for balanced parenting and interventions targeting both discipline and parental well-being to enhance children's mental health.