The tonoplast monosaccharide transporter (TMT) family plays essential roles in sugar transport and plant growth. However, there is limited knowledge about the evolutionary dynamics of this important gene family in important Gramineae crops and putative function of riceTMTgenes under external stresses. Here, the gene structural characteristics, chromosomal location, evolutionary relationship, and expression patterns ofTMTgenes were analyzed at a genome-wide scale. We identified six, three, six, six, four, six, and fourTMTgenes, respectively, inBrachypodium distachyon(Bd),Hordeum vulgare(Hv),Oryza rufipogon(Or),Oryza sativassp.japonica(Os),Sorghum bicolor(Sb),Setaria italica(Si), andZea mays(Zm). All TMT proteins were divided into three clades based on the phylogenetic tree, gene structures, and protein motifs. The transcriptome data and qRT-PCR experiments suggested that each clade members had different expression patterns in various tissues and multiple reproductive tissues. In addition, the microarray datasets of rice indicated that different rice subspecies responded differently to the same intensity of salt or heat stress. The Fst value results indicated that theTMTgene family in rice was under different selection pressures in the process of rice subspecies differentiation and later selection breeding. Our findings pave the way for further insights into the evolutionary patterns of theTMTgene family in the important Gramineae crops and provide important references for characterizing the functions of riceTMTgenes.