Abstract: Toll-like receptor (TLR) is a pathogen recognition receptor focused on by more people recently. It discriminates different pathogen-associated molecular patterns (PAMPs) and activates signaling cascades leading to immune responses. The specific TLR sign is conducted by adaptor proteins containing Toll–interleukin1 receptor (TIR) domains. The function is finished on MYD88 or no-MYD88/TRIF pathway, including five TIR adaptors: MYD88, MAL, TRIF, TRAM and SARM.