Moral emotion is a motivating factor for character realizations, which is a key point to examine the unity of children’s cognition and behavior. Based on a large-scale overall dynamic dataset on the moral development of Chinese children in 2016, 2019, and 2022 (sample sizes: 77,953, 77,367, and 79,914), using Sharp Index decomposition and logistic regression analysis, we have got the the following findings. Firstly, the types of Chinese children's moral emotion development are not balanced, with insufficient expression of sympathy. Secondly, the level of moral emotions initially increases and subsequently declines as age increases. The age of ten is a critical developmental milestone for moral emotions. Thirdly, structural differences in moral emotions among Chinese children exist based on gender and geographical region. Fourthly, there is a unique ecosystem logic by the intensity of the influence of the factors, in descending order of “individual-school-social support-family”. Life satisfaction, people who know the child, and the psychological environment of the school and the family are the high-impact factors. And there are differences in the influence of the different factors on the development of the moral-emotional development of the children of different genders and school segments.From the above findings, it is proposed that the cultivation of moral emotions in Chinese children should pay attention to the developmental imbalance of the types of moral emotions, the differences in the development of the group and the key influencing factors, optimize the ecosystem of children’s moral emotion development, seize the critical period of development, further clarify the focus of education, and enhance the relevance and timeliness.