Abstract: Charpy impact tests were done to three sizes of specimens cutting from L360MB steel sheet with thickness of 11.9 mm at different temperatures ranging from -60 ℃ to 20 ℃, to study the correlation between the impact energy of standard sized specimens and sub-sized specimens. The results show that the relationship between the specimen size and the ductile brittle transition temperature and performance of the sub-sized specimens at ductile brittle transition temperature were both more stable compared with the standard sized specimens. The change of the impact energy of sub-sized specimens at its ductile brittle transition temperature when the shim with proper thickness had been added was also studied. It was found that adding the shim or not had less effect on the impact test results.