Water-Filled Laparo-Endoscopic Surgery (WaFLES) is a surgical technique which is performed by irrigating the abdominal cavity with isotonic liquid. Since saline is used as perfusion fluid in WaFLES, the use of monopolar electrodes is limited. So design of devices for hemostasis in WaFLES environment is warranted. Therefore, we introduced a laser surgical robot system that enables a high precision laser irradiation for WaFLES. In this study, we optimized the laser power, scanning speed and scanning path of the laser surgical robot for automatic hemostasis and evaluated thermal damage and treatment time. As the result, we demonstrated the feasibility of a coagulation method that balances thermal damage and treatment time.