The transmission of 60 keV O+ ions through Al2O3 nanocapillaries at a series of different tilt angles is measured. The capillaries with diameters of 50 nm and 30 nm respectively and 10 μm in length are used. The angular distribution and the transmission yields of transported ions are investigated. Our results indicate both the existence of guiding effect when ions pass through the capillary and a significant dependence on the tilt angle. The results also show that the transmission yield increases as the diameter of capillary decreases，and the theoretical model used in our work explains it well.