In this paper, the new catalyst and catalyzed group, in microbial hydroxylation of carbon 11, are described as well as the mechanism of hydroxylation reaction in detail. Some amino acid residues in the active center of mono-oxygenases were pointed out to be the main factors to the hydroxylation. Moreover, the new technology and process of hydroxylation were also introduced. In respect of new technology, a brief introduction of some factors, such as growth regulator, magnetic field, ultrasonic wave and surface active agent, on hydroxylation reaction was given. While, with regard to the process, a special description of the immobilized cell in biophasic system was made.