Abstract: Taking deep ore-body of north mining area in Jinning phosphate No 2 pithead of Yunnan phosphate group corporation as engineering background，the stability of stope roof and surrounding rock and mining pressure movement's laws for different thickness of phosphate ore during underground mining process of deep phosphate were studied with FLAC3D numerical simulation software The numerical calculation results show that:①The weight of rock above the goaf，transferred to the new supporting points around the goaf Then the distressed zone was formed which is located in the roof，and bearing pressure zone was located ahead of the goaf and both sides ore wall beside the goaf With the advancing of the mining stope，the leading bearing pressure zone moved forward，and the affected areas by mining of the overlying strata is also expanded;②Under the inclination orebody，the stress state of the upper and lower part of the overlying strata above the goaf after excavating，were uneven and asymmetric，and the ground pressure in the upper part was more obviously then that in the lower part;③With the increasing of the thickness of the seam，the areas affected by mining of the overlying strata became bigger after the mined-out area was formed，but the ground pressure appears weakening stress concentration factor of the bearing pressure zone in front of the goaf and ground pressure became smaller The maximum stress concentration of the bearing pressure zone in front of the goaf is decreased，and its plastic zone expanded.

Key words: Mining of phosphate, Orebody thickness, FLAC3D, Numerical simulation, Mine pressure movement laws