Close first for the study of coal mining working face of weak rock deformation characteristics, to Xiong Jiawan coal mining face 20903 working face as the research background, based on the numerical simulation, theoretical analysis and field observation analysis close initial mining work face weak (C8) coal seam of coal and rock fracture, the stress changes and the characteristics of expansion deformation, etc. The results show that the fractal dimension of cracks rises steadily, rises rapidly and falls rapidly before and after the coal failure deformation, corresponding to three stages of failure deformation of C8 coal seam, from fracture generation to fracture stable development, from fracture stable development to bending subsidence, and from bending subsidence to fracture compaction. The first working face changed the maximum principal stress value and area of C8 coal seam, resulting in the failure and deformation of C8 coal seam. The expansion deformation of C8 coal seam shows the law of compression → expansion → stability. The maximum expansion deformation values of C8 coal seam are 12.1 and 11mm, which are located in the pressure relief expansion stability zone. According to the field observation, the weak coal and rock of C8 coal seam are stable as a whole, some coal and rock have broken fracture zone, and some roof rocks have become loose, which has no great influence on the stability of rock strata. The research results can provide reference for the first mining face with similar mining conditions.