Abstract: According to application of two-legs shield caving mining support, the necessary to strengthen its support capacity and significance to raise support heig ht were analyzed.ZFY17000/27/50D two-legs shield powerful caving mining support for large mining height face were designed for Shuangshan and Shenshupan coal m ines, and the major technical parameters were introduced.The relationship between external load position and supporting performance at 4.5 m supporting height were studied.The results showed that the caving mining support owned excellent support performance while the resultant force acting upon the working area of legs, and the working range of legs was 1 5761 804 mm distance from the back end of canopy.