Litchi (Litchi chinensis Sonn.) is one of the most distinctive fruits in South China and is one of the pillar industries of rural economy in South China. At present, the cultivated area of litchi in China is more than 533 000 hm² and the output is more than 2.3 million tons, accounting for more than 80% of the total cultivated area and more than 65% of the total output in the world. The panicle of litchi is paniculate, terminal, generally composed of cymes, with a length of 10-40 cm and 200-1500 florets. Excessive number of florets will consume tree nutrition and affect litchi fruit setting. Therefore, reducing the number of florets by regulating branches is an effective measure to improve fruit setting. SUPPRESSOR OF MAX2 1-LIKE 7 (SMXL7) is an important component of strigolactone signaling pathway and a new inhibitor with dual functions. SMXL7 is involved in leaf morphology regulating and branch development in Arabidopsis and rice. In order to identify the regulatory factors involved in the panicle branch development in litchi, LcSMXL7 the homologous of arabidopsis SMXL7 was cloned, the sequence of LcSMXL7 was obtained from RNA-seq data and the gene sequence, physicochemical properties, evolutionary relationships, conserved domain, tissue expression pattern, subcellular localization and gene function were analyzed. The open reading frame of LcSMXL7 was 3408 bp length, encoding 1135 amino acids. LcSMXL7 protein contained two CLP domains and one AAA_2 domain. The molecular formula, molecular weight and theoretical isoelectric point of LcSMXL7 was C₅₄₂₉H₈₆₃₂N₁₅₃₀O₁₇₁₅S₃₈, 123.99 kDa and 5.96. The Instability index, aliphatic index and grand average of hydropathicity of LcSMXL7 was 46.38, 83.74 and -0.305, respectively. LcSMXL7 was highly expressed in stems, seeds and leaves, followed by panicle, male flowers and pericarps, while the expression was low in female flowers, pulp and roots. Phylogenetic tree analysis showed that LcSMXL7 was closely related to SMXL7 protein from woody fruit trees sweet orange and mango. Subcellular localization analysis showed that LcSMXL7 was located in the nucleus, suggesting that it may participate in the regulation of gene expression as a transcription factor. Transgenic results showed that overexpression of LcSMXL7 in Arabidopsis could significantly increase the number of branches, indicating that LcSMXL7 could positively regulate the development of branches in Arabidopsis. We clarified the LcSMXL7 protein characteristics, tissue expression pattern, evolutionary relationships, conserved domain, subcellular localization and gene function, which would build a foundation for elucidating the molecular mechanism of LcSMXL7 in branch development.