Disclosed are 2-arylimidazo[1,2-a]pyridine-3-acetamide derivatives represented by formula I, their tautomer, racemate or optical isomer, their pharmaceutically acceptable salt, or their solvates, wherein R1, R2, R3 and R4 are defined as in the specification. Preparation methods of said compounds and use of said compounds in treating and/or preventing central nervous system disease associated with TSPO functional disorder
