Abstract: One complete cDNA of TLR named SiTLR-1(GenBank:HQ259110) was cloned from sea urchinStrongylocentrotusintermediusthrough degenerate primer PCR amplification and SmartTMRACE technology. Expression distribution in different tissue after challenge withVibriofortis,β-D glucosan,and dsRNA were assessed using quantitative real-time PCR (qRT-PCR).The full-length cDNA sequence of SiTLR-1 is 3637 bp,with 16 α-helix,33 β-sheet;composed of 1 transmembrane domain (725-750aa),a putative signal peptide (1-32aa), and a leucine-rich repeat (LRR).SiTLR-1 was assessed in all tested tissues (peristomial membrane,gut,coelomic fluid, muscle in Aristotles lantern,tube feet),the expression level in coelomic fluid was significantly higher than the others(P<0.05); the expression level of SiTLR-1 in coelomic fluid was strongly up-regulated after challenge withV.fortisand β-D glucosan,reach the highest point at 12 h; the expression level of SiTLR-1 showed no significant difference after challenge with dsRNA, just weakly up-regulated at 3 h. The findings showed that, TLR genes participated in the immune response of sea urchinS.intermedius, SiTLR-1 can specifically identify bacteria and β-D glucosan.