Abstract: According to a large area powered supports jammed and roof falling accident occasionally occurred in mechanized longwall mining face in China, the mi ne safety and high efficient production was seriously affected. With the case investigation, site measurement, simulation experiment and theoretical analysis, a deep sy stematic study was conducted on roof falling accident occurred condition, occurred mechanism and prevention and control countermeasures of large area powered sup ports jammed and roof falling accidents occurred in China. The study results showed that except for large area powered supports jammed and roof falling accident oCcu rred by the hard roof, three type conditions of shallow depth seam mining, seam mining under loose and pressurized aquifer and ultra high mining height mining would b e multiple ( easily) occurred conditions of large area powered supports jammed and roof falling accidents occurred in coal mining face in China. The breaking structure of the overburden key stratum due to the overburden strata loading too high to cause sliding and stability lost would be the basic sources of the large area powered sup ports jammed and roof falling occurred in the coal mining face under the above three type conditions. The prediction on danger area according to the overburden key str atum under certain mining condition would be the prerequisite to the prevention and control of the large area powered supports jammed and roof falling disaster occurre d and rational designed working resistances of powered support would be effective technical measures to prevent and control powered supports jammed and roof fallin g. Under partial condition, only relied on the working resistances of the powered support increased would be hard to realize the prevention and control of the large area powered supports jammed and roof falling disaster and the prevention would need other measures to be conducted.