A multi-pass traveling-wave Ndglass amplifier with a duct for coupling is introduced. Based on the analysis results of the relations between structural parameters and coupling efficiency of dust, a pumping structure contains 8 laser diode arrays is designed, and it′s output status is simulated. The pumping structure converges pumping energy generated from 168 bars on the area of 8 mm×8 mm, and about 7.3 J output energy is obtained. According to the output characters of the pumping structure, a rotated multi-pass traveling-wave amplification structure is designed, which based on the working material of Ndglass, and 15 mJ output energy is obtained with a 300 μJ injected signal laser.