Abstract: Rock mechanics parameters and single well in-situ stress are the basic parameters for basin tectonic stress field simulation, oil and gas field drilling and completion and reservoir fracturing stimulation design. Based on the experiment of rock mechanics and array acoustic waves, the rock mechanics parameters and in-situ stress of the carbonate reservoirs of the Lower Paleozoic Ordovician Yingshan Formation and Yijianfang Formation in the Shunbei 4 zone were analyzed. The results show that the Young's modulus of the Yijianfang Formation and the Yingshan Formation in the Shunbei 4 zone is 50-89 GPa, the compressive strength is 99-136 MPa, and the Poisson's ratio is 0.25-0.32. Combined with logging interpretation of reservoir classification, the differences in rock mechanics parameters of different reservoir types were compared and analyzed. From type I, type II, type III to non-reservoir, the Young's modulus and compressive strength of carbonate rock increased significantly, while Poisson's ratio is not much different. The maximum horizontal stress of the Yijianfang Formation and the Yingshan Formation in the Shunbei 4 zone is 200-225 MPa, and the minimum horizontal stress is 125-160 MPa; from type I, type II, type III to non-reservoir, the maximum horizontal principal stress of carbonate rocks The maximum horizontal maximum horizontal stress increases significantly, while the minimum horizontal stress has little difference. There are early cracks and caves in carbonate rocks, which significantly weaken the rock's ability to resist external forces and reduce the rock's compressive strength and Young's modulus.