Abstract: Casing deformation in the process of horizontal well fracturing is one technical difficulty that exists in domestic shale gas development in recent years. In order to investigate the casing deformation mechanisms of horizontal well fracturing and control the occurrence of casing deformation, this paper analyzed the fracturing process of shale-gas horizontal well. Then, based on the reservoir geological characteristics of Weiyuan 202 and Weiyuan 204 Blocks, the main causes and characteristics of casing deformation were clarified by analyzing the basic data of over 100 fractured horizontal wells. It is shown that the main factors inducing the casing deformation in the fractured horizontal wells in Weiyuan are reservoir geological characteristics, fracturing design and in-situ stress, and most of the casing deformations lie in the sweet spot zones with developed bedding fractures. Some casing deformation wells in the Weiyuan 202 Block are related to the situation that the horizontal section penetrates the competent Wufeng Formation, and some casing deformation points are located near target A. In the Weiyuan 204 Block, the casing deformation points in fractured horizontal wells also mostly lie in the sweet spot zones and they are mainly located in the sweet spot zones near target A. The research results lay the foundation for the further prediction and control of casing deformation.