The insect olfactory system employs a diverse array of olfactory-related proteins to facilitate odor detection and signal transduction. Their expression and regulation are crucial for mediating communication between themselves and environments. Lytta sifanica (Coleoptera: Meloidae) is one of the most important economic pests and is famous for producing a toxic substance cantharidin. However, the genes underlying olfactory sensation are lacking in this Blister Beetle. In this study, the transcriptomes of adult L. sifanica antennae were sequenced and analyzed. A total of 70 chemosensory genes, including 17 odorant binding proteins (OBPs), 5 chemosensory proteins (CSPs), 13 gustatory receptors (GRs), 17 odorant receptors (ORs), 13 ionotropic receptors (IRs) and 5 sensory neuron membrane proteins (SNMPs) were identified based on sequence homology analysis and phylogenetic reconstruction. The expression patterns of all candidate genes in the antennae of adults, head, mouthparts, pronotum, foreleg tarsus, abdomen skin, wings were confirmed by RT-PCR. The analyses demonstrated that all protein families related to olfaction are widely expressed in examined tissues. However, the expression patterns varied for different families. Eleven members are predominantly expressed in the antennae (Lsif_OBP1/2/19d, Lsif_OR2/20/49b, Lsif_IR2a, Lsif_GR7/127, Lsif_CSP1, Lsif_SNMP2/4). Twenty-two members were exclusively expressed in the mouthparts (Lsif_OBP70/56d2, Lsif_GR12a/21/28a/68a), foreleg tarsus (Lsif_OR6/67c, Lsif_GR12, and Lsif_OBP2) and were abundant in the non-olfactory tissues head (Lsif_OBP99a, Lsif_OR9a/49b, Lsif_IR25a/56e, and Lsif_CSP6), pronotum (Lsif_OBP5/C20, Lsif_Orco3, Lsif_OR13, and Lsif_IR7), abdomen skin (Lsif_SNMP5), suggesting their various functions in the olfactory system of L. sifanica. This research offers an extensive resource for investigating the chemoreception mechanism in beetle L. sifanica.