High-order Laguerre-Gaussian (LG) mode output, the angular indices m of which can be tuned con. veniently, is generated in an end-pumped Nd:YVO4 laser which has strong spherical aberration (SA) in its cavity. The experimental results are explained based on the beam radius and ring-shaped beam width of the LG mode beam. It is found that the SA-induced actual focal point displacement between different modes is essential for single high-order mode operation, while the SA and the beam width determine the loss on a certain mode and whether it can oscillate. For high-order mode operation, long-focal lens is used to decrease the SA and resultant loss on high-order modes and increase the pump power to enhance the laser gain. A maximum angular index m of ±95 is ob. tained with radial index of p of 0. With short-focal lens to enhance the SA and corresponding mode-selecting capa. bility, LG mode output with non-zero radial indices is obtained.