In this study, an electron-scattering device was fabricated to practically use the ultra-high dose rateelectron beams for the FLASH preclinical research in Dongnam Institute of Radiological and MedicalSciences. The Dongnam Institute of Radiological and Medical Sciences has been involved in the investigationof linear accelerators for preclinical research and has recently implemented FLASH electronbeams. To determine the geometry of the scattering device for the FLASH preclinical research with a 6-MeV linear accelerator, the Monte Carlo N-particle transport code was exploited. By employing thefabricated scattering device, the off-axis and depth dose distributions were measured with radiochromicfilms. The generated mean energy of electron beams via the scattering device was 4.3 MeV, and thesymmetry and flatness of the off-axis dose distribution were 0.11% and 2.33%, respectively. Finally, thedoses per pulse were obtained as a function of the source to surface distance (SSD); the measured doseper pulse varied from 4.0 to 0.2 Gy/pulse at an SSD range of 20e90 cm. At an SSD of 30 cm with a 100-Hzrepetition rate, the dose rate was 180 Gy/s, which is sufficient for the preclinical FLASH studies.