Atomic shear interferometry is an emerging matter wave interferometric technique developed in recent years, which has demonstrated growing applications in fundamental physics and practical metrology due to its exceptional precision and real-time measurement capabilities. However, the tilt of the detection system represents one of the critical sources of systematic errors in high-precision atomic shear interferometric measurements. To address this challenge, we first make a comprehensive theoretical analysis and quantitative evaluation of the impact of detection system tilt on interferometric measurements, and then experimentally implement a two-stage strategy for tilt measurement: using the plumb line method during system installation and using the atomic interferometric phase shift method during operational measurements. Regarding to the plumb line method, the tilt measurement resolution is 0.6 mrad, and the overall measurement accuracy is approximately 1–2 mrad considering the influence of various types of errors. Regarding to the atomic interferometric phase shift method, we develop specialized phase shift reference systems to measure system tilts for different interferometer configurations. Specifically, for single-species atom interferometers designed for gravity, gravity gradient, and rotation measurements, we propose and implement the atomic interferometric phase shift method with simultaneous dual-internal-state detection, achieving a tilt measurement resolution of 0.3 mrad and reducing tilt-induced errors in gravity measurements to the level of 10^-10 g. For dual-species atom interferometers used in equivalence principle tests, we develop an alternative detection atomic interferometric phase shift method for real-time monitoring, achieving a tilt measurement resolution of 0.3 mrad, and satisfying the differential gravity measurement requirements at the 10^-13 g level. The research methods used in this paper will provide references for solving the problems of systematic errors caused by the tilt of the detection system in atomic shear interferometers.