In order to study the efficient coupling system and its stimulation method for the end-pumped structure of high power laser diode (LD) arrays, a hollow duct coupling system for 12 kW LD pumped Yb∶YAG laser was designed by ray tracing method. Based on the LD bar’s structure and beam parameters, the source models about LD bar and array were simulated by arranging emitters with Gaussian beam. In the coupling system, two lenses and silver-coated flat reflectors were used to concentrate pumping radiations. The experimental results have confirmed that the coupling system achieve a high efficiency and the energy distribution is agreed well with the theoretical analysis. The coupling efficiency of the system is 92.3% on the condition of 94% reflectivity of reflectors. The coupling beam shows excellent propagation characteristics and large uniform pump field on the surface of gain medium which meet the requirement of the Yb∶YAG laser very well.