The interaction between aminoacyl-tRNA synthetases(aaRS) and tRNAs maintains the fidelity of protein biosynhesis. The specificity of recognition of tRNAs by aminoacyl-tRNA synthetases(aaRS) depends on the definite catalytical domain of aaRS and the distinctive tertiary structural comformation of tRNAs. Anticodon and acceptor stem (including position 73) play key roles in most recognition of tRNAs by aminoacyl-tRNA synthetases, other positions such as variable pocket,variable (stem) loop, even modified nucleotides are also important in some recognition.