Aminoacyl-tRNA synthetases (ARS) are the oldest enzymes in the evolution. The amino acids are transferred to the cognate tRNAs by the aminoacyl-tRNA synthetases, and then involved in the synthesis of the protein. This process is very important to keep the stability and variety of the lives. With the coming of the post-genome research, one of the main objectives becomes to illustrate the structures and the function of the aminoacyl-tRNA synthetases. Based on the data from the structure biology and the bioimformatics, the multi-ARS complex seemed to be the main form in the eukaryote. In addition, mammalian ARSs consist of a sophisticated macromolecular network with the auxiliary proteins or the elongation factors. The recent discoveries show that aminoacyl-tRNA synthetases not only are the most important enzymes to the synthesis of the protein, but also are involved in the diverse cellular processes, such as regulation on the transcription and translation level, RNA splicing and trafficking, apoptosis, angiogenesis and inflammation.