The sintering workers have never stopped the research on lowering the air leakage of sinter machine, in which some improvements for control of air leakage of the slide seal in the middle part of sinter machine have been made, however, the desirable outcome is not achieved. Through the research and application of a new type of slide seal (non-rigid oil-free slide seal), the air leakage of the slide seal of sinter machine is reduced by an average of 9.7%, and the negative pressure of the sintering main pipe increases by an average of 1.5kPa, thus the sinter output and sinter quality are somewhat improved and the zero consumption of the grease for slide seal is realized.