Abstract: In order to study the influence of loose bed accounted for depth on surface subsidence characteristics in thick unconsolidated layers, on the basis of the surface movement observation data of Zhaogu Coal Mine Area, the influence of loose bed accounted for depth on characteristics of surface subsidence, the maximum ground sinking speed, the maximum ground subsidence velocity lag distance and the influence of duration of ground surface at different stages was analyzed respectively under the condition of mining under thick unconsolidated layers. It was concluded that under the condition of thick loose bed, with the increase of loose bed accounted for depth, surface subsidence coefficient increases from 0.67 to 0.96, increasing nearly 43.3%; coefficient of maximum subsidence velocity increases from 1.26 to 1.49, increased by 18.4%; the lag distance of maximum subsidence velocity reduced from 188 m to 97 m, by almost 48.4%. At last, through the numerical simulation, the general rule of the ground surface displacement by the proportion of the loose layer was got, and the prediction formula of the main moving parameters which suit for the geological condition were fitted.