The thin-disk shape laser crystal is the core component of the thin disk laser. In the experiment, we found that the crystal edge is prone to abnormal high temperature in the operation, which causes the thin disk laser's conversion efficiency to decrease, and even the make crystal cracks. In order to solve this problem, two aspects that may cause this effect are researched during the disc crystal manufacturing process, and finally determined that the splash of solder during the packaging process is the main cause of this problem. In the end, we used the edge chamfering method to eliminate this problem, and the finally obtained thin disk crystal can reduce the temperature by 50% and increase the conversion efficiency by 15% when the laser operates.