【Objective】Leaf blade is an important factor of plant type, which is directly related to leaf photosynthetic area and light energy utilization. Flag leaf is most prominently in the formation of rice production. Study of the genes which regulate flag leaf development in rice is of very significance in rice functional genomics research and molecular breeding. A novel flag leaf mutant has been identified and the results of study will provide a foundation for the research of leaf morphological formation and plant type breeding in Oryza sativa L.【Method】A dwarf and curled flag leaf mutant (dcfl1) was discovered from the progeny of indica restorer line Jinhui10 with seeds treated by ethyl methane sulfonate (EMS) and the traits of dwarf and curled flag leaf base inherited steadily after multi-generations’ self-fertility. The second leaf sheath was observed by scanning electron microscopy (SEM) at the three-leaf stage. The flag leaf base was used for paraffin section at the booting and heading stages. At the blooming stage, the characteristics of chloroplast pigment of the flag, second and third leaf blades were measured. At the maturity stage, agronomic traits such as plant height, panicle length, efficient panicle per plant, seed number per panicle, filled grain number per panicle, seed setting ratio, and 1000-seed weight were measured. The dcfl1 was crossed with indica sterile line Xinong 1A, and the F1 and F2 generations were used for genetic analysis. Additionally, gene mapping was performed based on the recessive individuals of the F2 generation of Xinong 1A/ dcfl1.【Result】The dcfl1 was dwarf in all phases of plant development. The cell length of the 2nd leaf sheath surface of the dcfl1 was significantly shorter than the wild type. The panicle length, the first and the second internode of the dcfl1 were all significantly shorter than those of the wild type. The dcfl1 displayed a severe curl at the base of flag leaf blade after the heading stage, while the upper of flag leaf blade was nearly normal in the flag leaf. Meanwhile, the other leaf blades appeared as normal as the wild type. No significant differences were detected in grain number per panicle, filled grain number per panicle, seed setting rate and 1000-seed weight between the dcfl1 and the wild type. However, the number of the tiller in the dcfl1 was more than the wild type and the efficient panicle per plant was increased significantly than the wild type. Having the dark green leaves, the contents of chlorophyll a and total chlorophyll in the dcfl1 increased significantly compared with those of the wild type for the flag leaves, the second and the third leaves. Genetic analysis indicated that the dwarf and curled flag leaf traits of dcfl1 were controlled by a recessive nuclear gene. Based on the F2 population derived from a cross between the dcfl1 and an indica sterile line, Xinong 1A, the gene was fine mapped on chromosome 3 between InDel marker Ind03-11 and Ind03-6 with the physical distance 78 kb, containing fifteen annotated genes.【Conclusion】The dcfl1 is a novel recessive dwarf and curled flag leaf mutant coming from EMS-inducement. The DCFL1 was mapped on chromosome 3 with 78 kb physical distance. These results will provide a foundation for map-based cloning of DCFL1 gene and understanding of the molecular mechanism of the rice flag leaf.