To explore the coupled impacts of loading rate and confining pressure on the deformation, strength, and microcracking mechanisms of sandstone, triaxial compression tests were carried out under four distinct loading rates (0.001, 0.01, 0.1, and 1.0 mm/s) and four confining pressures (0, 20, 40, and 60 MPa), with concurrent monitoring of acoustic emission (AE). Leveraging moment tensor theory, the source mechanisms and microcrack propagation patterns of AE events were inverted. The findings reveal that as the loading rate rises, the peak strength increases from 27.18 MPa to 34.32 MPa under uniaxial compression and from 143.69 MPa to 164.34 MPa under a confining pressure of 60 MPa. Concurrently, the elastic modulus increases from 9.03 GPa to 10.88 GPa and from 16.74 GPa to 18.02 GPa, respectively, showing a positive linear relationship with the logarithmic loading rate. The peak strain is insensitive to loading rate under low-to-medium confining pressures but decreases by 18.42% under 60 MPa when the loading rate increases from 0.001 mm/s to 1.0 mm/s, revealing an inhibitory effect of high confining pressure combined with high loading rate on plastic deformation. Macroscopically, the failure mode transitions from brittle tensile splitting to ductile shearing as confining pressure increases. Analysis of AE source mechanisms indicates that shear cracks are predominant, constituting 55.3%-72.4% of all events, with their proportion rising with loading rate. The total number of microcracks declines with increasing loading rate, from 1145 to 698 at a confining pressure of 20 MPa, suggesting that rapid loading inhibits full crack propagation. The AE b-value, which describes the slope of the frequency-magnitude distribution of AE events, decreases from 1.99 to 1.82 under 20 MPa confining pressure and from 1.89 to 1.68 under 60 MPa confining pressure as the loading rate increases, indicating a higher proportion of large-scale cracks and a more simplified crack network under rapid loading. This study deepens the comprehension of excavation rate effects in deep rock masses and provides a theoretical foundation for engineering stability assessment and disaster early warning.