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Litchi possesses unique flower morphology and adaptive reproduction strategies. Although previous attention has been intensively devoted to the mechanisms underlying its floral induction, the molecular basis of flower sex determination remains largely unknown. MADS-box genes are promising candidates for this due to their significant roles in various aspects of inflorescence and flower organogenesis. Here, we present a detailed overview of phylogeny and expression profiles of 101 MADS-box genes that were identified in litchi. These <i>LcMADS</i>s are unevenly located across the 15 chromosomes and can be divided into type I and type II genes. Fifty type I MADS-box genes are subdivided into Mα, Mβ and Mγ subgroups, while fifty-one type II <i>LcMADS</i>s consist of 37 MIKC^C -type and 14 MIKC *-type genes. Promoters of both types of LcMADS genes contain mainly ABA and MeJA response elements. Tissue-specific and development-related expression analysis reveal that <i>LcMADS51</i> could be positively involved in litchi carpel formation, while six MADS-box genes, including <i>LcMADS42/46/47/75/93/100</i>, play a possible role in stamen development. GA is positively involved in the sex determination of litchi flowers by regulating the expression of <i>LcMADS51</i> (<i>LcSTK</i>). However, JA down-regulates the expression of floral organ identity genes, suggesting a negative role in litchi flower development.