Abstract: In order to study law of the surface movement and deformation under thick unconsolidated strata, according to the observation data of surface movemen t observation station in Kailuan mine area, parameters of probability integral method were obtained by methods of ftting analysis, and the relations between each para meter and condition of geology and mining were obtained. Meanwhile, law of the surface movement and deformation were discussed with the help of the UDEC softwar e of numerical simulation. The study results showed that the thickness of alluvium was main influence factors about surface movement and deformation, in the condition of mining under thick unconsolidated strata, surface movement and deformation was serious. Most of the value of the surface subsidence coefficient was greater than 0.90, the variation range of deviation of inflection point was 7 ~ 55 m, discontinuous deformation would be appeared easily on the surface, then more danger would be given rise to mining under thick unconsolidated strata. So mining technology measures, such as increasing safety coal and rock pllar, and so on, should be adopted to i nsure safe-mining under railway, water body and building.