Abstract: In order to study the fracture characteristics of limestone roof at short-wall fully-mechanized mining face of thin coal seam and realize roof safety and economical control, theoretical calculation, numerical simulation and field observation were applied to analyze the first fracture distance characteristics and behavior laws. The results demonstrate that the first and periodic weighting distance were 40.7 m and 15.5 m respectively, dynamic load coefficient is about 1.25, the limestone roof appears the characteristics as typical "O-X" model fracture and caving come across square with the working face advancing, the influence time and scope decrease obviously and appear entire weighting type by applying the high power fully-mechanized equipments to enhance the advancing speed.