Thermal homogeneity and low wave-front distortion are the main problems affecting the beam quality of high power Nd:YAG thin disk laser which should be solved through packaging technique. The thermal stress of thin disk produced in the process of welding was analysed and the thermal distribution was stimulated. Φ80 mm YAG thin disk laser gain medium and micro channel cooler(MCC) were connected by optimized packaging technology. The disk laser was tested by scanning acoustic microscope (SAM) and laser interferometer. The results show that solder layer is homogeneous and void-free, peak-to-valley(PV) departure of optical surface is less than 1 μm and root-mean-square(RMS) is less than 0.15 μm in the circle diameter of 60 mm. On the basis of this packaging technique, high beam quality 2.3 kW output power was extracted with one disk laser.