Toll-like receptors (TLRs), a large family consisting of at least 10 members, are evolutionarily conserved to recognize pathogen-associated molecular patterns (PAMPs). TLRs activation not only initiates innate immunity, but also regulates enhance antigen-specific acquired immunity, and thus associates innate and adaptive immunity. In recent years, studies on the TLRs signaling, especially their negative regulation, rapidly progressed. TLRs signaling pathway and their roles in regulating immune responses against invading pathogens were reviewed.