Superfine pulverized coal reburning (MCR) technology is one of most promising methods to reduce NOx emission. The experimental study of some influencial factors on NOx emission of MCR technology has been conducted. Results show that a remarkable NOx reduction efficiency of MCR between 50 % and 70 % is achieved for all kinds of coal. Lignite or bituminous coal with high volatile is very good reburning fuel. Compared with conventional pulverized coal reburning, NOx reduction efficiency will increase with the diminution of particle size of reburning fuel,and MCR is very successful in further reducing NOx emission by over 10%. NOx emission will be depressed in different case along with the cncrease of fraction of reburning fuel.