Abstract: As an important vegetable crop, tomato plays a crucial role in modern agriculture production and scientific research. Leaf is a nutrient organ for plant development, and the leaf color affects the efficiency of photosynthesis and respiration, which is closely related to tomato fruit yield. Leaf color mutations have complex molecular mechanisms, and mutated genes can directly or indirectly interfere with pigment synthesis and stability, leading to the change of leaf color. There are many research results on the physiological and biochemical mechanisms, gene localization and cloning, and external environmental influencing factors of leaf color variation in model crops; however, there is still limited research on leaf color mutants in vegetable crops. In order to gain a deeper understanding of the photosynthetic system structure, functional genomics, and genetic breeding of tomatoes, this article focuses on exploring the formation mechanism of tomato leaf color variation and the identification of key genes. This study not only helps to improve the identification and utilization of high-quality tomato germplasm resources, but also analyzes the relationship between tomato photosynthesis and pigment content, thereby revealing the mechanism of tomato leaf color formation. This article provides a review from the following aspects: types of leaf color mutants, genetic patterns of leaf color mutants, formation mechanisms of leaf color mutants, physiological studies of leaf color mutants, multi-omics analysis and epigenetics. Through these research advances, we explored the existing problems in the study of tomato leaf yellowing genes and provided prospects for future research directions, with an aim to provide theoretical basis and solutions for tomato breeding practice, and further promote the development of related fields.