In view of the phenomenon that mining under shallow buried thick coal seam in western mining area of China is prone to severe mine pressure and serious surface subsidence damage, with the 22021 working face of a mine in western China as the research background，the structural mechanics model of “inclined step cutting body” under shallow buried thick coal seam was proposed，and the conditional equation of structural instability and the formula for solving the size of support force were obtained.The PFC numerical simulation and engineering application were verified，and the influence of this structure on the development law of overlying rock mining-induced cracks was analyzed.The results show that the main factors affecting the structural stability of the “inclined step cutting body” are rock block size and rotation angle，and the stability of the structure directly affects the development of overlying rock mining-induced cracks.In the process of coal seam mining，the development of overlying rock cracks is characterized by oblique angle extension and periodic lateral extension.Before the structural instability of “inclined step cutting body”，the development stage of the cracks is in a slow growth period.After the structural instability，the number of mining-induced cracks in weathered rock increases sharply，and the development stage enters a period of rapid growth.The structural stability directly affects the development of mining-induced cracks in weathered rock，thereby affecting the destruction of surface subsidence.The number of overlying rock mining-induced cracks has experienced a slow growth period and four rapid growth periods.In the slow growth period，the number of cracks shows an exponential relationship with the increase of working face advancing distance.In the rapid growth period，the number of cracks shows a linear relationship with the increase of working face advancing distance.The research results provide a basis for mining damage protection and surface ecological restoration.