Yingyangbao (YYB) is a soy-based micronutrient-fortified powder used in the Nutrition Improvement Project on Children in Poor Areas of China. After the baseline study in 2012, YYB intervention gradually spread to 21 provinces in China. From 2015 to 2020, a secular trend study was carried out to evaluate the body growth and nutritional status of 6–23-month-old infants and young children (IYC) under YYB intervention. The aim of this research was to investigate whether YYB intervention was associated with the improvement of body growth and development in large populations from broad areas with national and multi-year survey results. The anthropometric data collected in the baseline study and cross-sectional surveys were compared, and the correlation between YYB intake amount and body growth were analyzed. Compared with the results of the baseline study, the 6–23-month-old IYC under YYB intervention showed a significant increase in body weight, body length and Z scores since 2015, and the stunting rate decreased from 9.7% in 2012 to 5.3% in 2020. Significantly positive correlations were observed between the YYB intake amount and the body growth indicators. Therefore, YYB intervention was associated with the improvement of body growth and nutrition status of Chinese IYC. In the future, long-term and continuous efforts are still needed to further reveal the health benefits of YYB in depth.