Objectives:To investigate the screening status of warning signs for mental and behavioral development (WS) and influencing factors of infants and young children (IYC) in poverty eliminated regions of Henan Province.Methods:This study was a cross-sectional study. A total of 15 680 IYC aged 6-23 months from 51 poverty eliminated counties in Henan province from June to September of 2023 were selected through a multi-stage random sampling method. IYC′s early warning signs were screened using the WS checklist (WSC). Children′s socio-demographic characteristics, maternal information, birth status, and illness conditions such as fever and diarrhea within 2 weeks were measured through a uniformly designed questionnaire. All participants also received the measurement of height, weight, and hemoglobin concentration level. Logistic regression model was used to explore the influencing factors of positive WSC and conducted sensitivity analyses.Results:Among the sample of 15 680 IYC, there were 8 462 boys (53.97%) and 7 218 girls (49.03%), with their age of (15±5) months. A total of 291 (1.86%) IYC were positive in WSC. Parenting risk ( OR=5.07, 95% CI 3.93-6.52, P<0.001) and preterm birth ( OR=1.63, 95% CI 1.06-2.52, P=0.027) were both positively associated with the odds of WSC′s positivity. Being girls ( OR=0.66, 95% CI 0.52-0.85, P=0.001), age (12-17 months, OR=0.47, 95% CI 0.35-0.62, P<0.001; 18-23 months, OR=0.40, 95% CI 0.30-0.54, P<0.001), and maternal educational level (junior high school, OR=0.46, 95% CI 0.32-0.66, P<0.001; senior high school or vocational high school, OR=0.35, 95% CI 0.23-0.56, P<0.001; college and above, OR=0.36, 95% CI 0.23-0.57, P<0.001) were all negatively associated with the risk of WSC′s positivity. Sensitivity analyses demonstrated that, after excluding anemic children, the association between preterm birth and WSC′s positivity was not significant ( OR=1.54, 95% CI 0.95-2.49, P=0.081). Despite this situation, being girls, age and maternal educational level were still negatively associated with the odds of WSC′s positivity (all P<0.05); preterm birth, parenting risk were remained positive associated with the risk of WSC′s positivity (all P<0.05) either by excluding children with protein-energy malnutrition or 2-week morbidity, or using prevalence ratio instead of OR. Conclusions:Among the IYC in poverty eliminated regions of Henan Province, the risk of positivity of WSC was higher for those IYC with parenting risk, preterm birth, boys, younger age, and lower maternal education level. These influencing factors, such as gender, age, preterm birth, parenting risk and maternal educational level, were in certain stability across different IYC characteristics and estimation models.