Many microorganisms could use nonribosomal peptide synthetases (NRPSs) to synthesize various bioactive peptides with complicated structures. Because of their special physical-chemical and pharmacological properties, the nonribosomal peptides (NRPs) had been extensively studied, and would have great potential for commercial application. NRPSs are composed of many iterative modules whose different assembling orders determine the specificity of amino acid sequences of their peptide products. The NRPs are assembled by NRPSs via multiple-carrier thiotemplate mechanism, and the substrate specificity of NRPSs is determined by both adenylation domain and condensation domain. Recently, many expected peptides were synthesized using natural whole NRPSs, some specific domains of NRPSs, or novel NRPSs which were constructed by the combination or hybrid combination of specific modules or domains of some known NRPSs.