Abstract：By the industrial mining experiments and observed data of working faces No.51101(240 m in length) and No.51104(300 m in length) in Shangwan coal mine of Shenfu—Dongsheng mining district，the effects of increasing face¢s length on underground pressure¢s behaviors were explored，and the conclusions are drawn as follows：(1) weighting span becomes shorter；(2) cycle weighting strength is relaxed；(3) the rock pressure distribution is shown that the quadric parabola relations can be used for the working face¢s middle point as symmetrical axis(i.e. coordinate origin)；(4) the regression relation between maximum resistances and initial ones is liner；and (5) the support¢s loads in non-weighting period and underground pressure behavior with increasing face¢s length are enhanced，and roof weighting impact load was larger than the support¢s maximum resistance for large mining height and supper-long faces.
