Tiltmeter mapping technology infers hydraulic fracture geometry by measuringfracture-induced rock deformation, which recorded by highly sensitive tiltmeters placed atthe surface and in nearby observation wells. By referencing Okada's linear elastic theory andGreen's function method, we simulate and analyze the surface and downhole deformationcaused by hydraulic fracturing using the homogeneous elastic half-space model and layeredelastic model. Simulation results suggest that there is not much difference in the surfacedeformation patterns between the two models, but there is a significant difference in thedownhole deformation patterns when hydraulic fracturing penetrates a stratum. In suchcases, it is not suitable to assume uniform elastic half-space when calculating the downholedeformation. This work may improve the accuracy and reliability of the inversion results oftiltmeter monitoring data.