Abstract: In order to study the impact of upward-mining angle on mining coal wall piece in wutongzhuang mine,the mechanism of wall piece is analyzed and is defined as gravity slide destruction;Use UDEC(Universal Distinct Element Code)discrete element numerical software to analyze the condition of the mining coal wall piece in different upward-mining angles,thus obtaining the tipping point of wall piece angle and the depth of the coal wall piece;The tipping point of wall piece angle is verified to be around 12° combining with the wall piece angle and depth resulting from field statistic and ultrasonic testing,and the depth of wall piece is 0.5mwithin a certain range of upward-mining angle,wall piece is mainly concentrated in upper coal wall,which have certain guiding significance for the research of coal wall piece and roadway support under the condition of upward mining.