A new coupling method is put forward for high power LDA end-pumped large-aperture amplifiers. The LDA is inscribed on a sphere and then a duct is added adjacent to it. Three-dimensional ray-tracing program is used to simulate the features of the new coupling method. Simulation results show that when the area contraction coefficient is about 30, deposition efficiency in the gain media as high as 93.7% can be achieved; When the emitting area is not less than the aperture of the duct, uniform and top-hat distribution is obtained. When several stacks are spliced to make an inscribing area, amplifiers with larger aperture can be end pumped. When stacks in LDA is placed as m×n(m≠n) arrays, uniform and top-hat distribution is also obtained. In the LDA coupling experiment, the output is top-hat distributed at the end of the duct and the coupling efficiency is 85.4%.