Abstract: In order to solve serious mine strata pressure behavior and roof cutting powered support jammed accident frequently occurred in the fully- mechanized t op coal caving mining face in Tiebei Mine, the site observation and theoretical analysis showed that special roof condition and poor powered support performances wer e the major factors to cause the roof cutting powered support jammed accident. The KJ21 mode roof disaster monitoring and measuring early warning system was appli ed to the monitoring and analysis on powered support initial support force, a circulation end resistance, safety valve opening, periodical roof weighting distance, powere d support no pressure keeping, powered support unbalanced and other key indexes. With a mathematical statistics and analogy method applied to the analysis on the monitored and measured data, five major factors to cause the roof cutting powered support jammed accident were obtained and thus the measures to prevent and contr ol the roof cutting powered support jammed accident occurred in the coal mining face were put forward. The results showed that the monitoring and analysis conducted on the powered support performances of the coal mining face would be favorable to prevent and control the roof cutting powered support jammed accident occurred and could make the month production of the coal mining face increased from 170 000 t to over 250 000 t.