Leaves are pivotal organs for photosynthesis, respiration, and transpiration in plants. Their morphological development is jointly influenced by genetic, environmental, and evolutionary factors, while their size significantly impacts crop growth, yield, and quality. Investigating leaf developmental mechanisms, understanding environmental influences on leaf formation, and defining the optimal leaf size range are of great importance for agricultural production. However, numerous challenges remain in plant leaf development research, including gene interaction networks, coupled effects of multiple environmental factors, classification of optimal leaf size ranges, and applications in breeding-all of which require further breakthroughs. Therefore, this review employs a literature-based research approach to summarize recent advances in the regulatory mechanisms and influencing factors of leaf development across various plant species. It analyzes the current research status, trends, and key issues concerning leaf size, aiming to provide a reference for future studies. The main aspects covered include:（1）Mechanisms of leaf morphogenesis, elucidating the three stages of leaf shape formation. （2）Regulatory mechanisms of leaf development, primarily summarizing cellular and molecular-level control pathways. （3）Factors influencing leaf morphology, including genetic and environmental determinants. （4）Technologies applied in leaf research, encompassing cutting-edge techniques, traditional experimental methods, instruments, and analytical software, along with their applications in leaf development studies.