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The Sugars Will Eventually be Exported Transporters (SWEET) family is a class of sugar transporters that play key roles in phloem loading, seed filling, pollen development and the stress response in plants. Here, a total of 18 <i>JcSWEET</i> genes were identified in physic nut (<i>Jatropha curcas</i> L.) and classified into four clades by phylogenetic analysis. These <i>JcSWEET</i> genes share similar gene structures, and alternative splicing of messenger RNAs was observed for five of the <i>JcSWEET</i> genes. Three (<i>JcSWEET1</i>/<i>4</i>/<i>5</i>) of the JcSWEETs were found to possess transport activity for hexose molecules in yeast. Real-time quantitative PCR analysis of <i>JcSWEETs</i> in different tissues under normal growth conditions and abiotic stresses revealed that most are tissue-specifically expressed, and 12 <i>JcSWEETs</i> responded to either drought or salinity. The <i>JcSWEET16</i> gene responded to drought and salinity stress in leaves, and the protein it encodes is localized in both the plasma membrane and the vacuolar membrane. The overexpression of <i>JcSWEET16</i> in <i>Arabidopsis thaliana</i> modified the flowering time and saline tolerance levels but not the drought tolerance of the transgenic plants. Together, these results provide insights into the characteristics of <i>SWEET</i> genes in physic nut and could serve as a basis for cloning and further functional analysis of these genes.