Fairness plays a pivotal role in moral development, and need-based allocation, as a form of equitable resource distribution, entails allocating resources to individuals with greater need. Children’s need-based behavior is influenced by a variety of factors, including situational, personal, and social aspects. Currently, the motivational explanations for children’s need-based allocation are not fully understood. Here, we present an explanatory model for comprehending children’s motivation to allocate based on needs. We propose that children’s motivation to engage in need-based behavior is a dynamic process that unfolds in three stages: the balancing tendency stage (4-5 years old), the balancing-altruistic dual-motivation stage (6-7 years old), and the altruistic tendency stage (8 years old and above). In conclusion, we offer a perspective on future research directions aimed at gaining a deeper understanding of the developmental process underlying children’s fair decision-making.