Abstract: A new type of W-shaped specimen for determining T₀ was designed based on the W-shaped specimen developed earlier in China. The test technology of W-shaped specimen forT₀ measurement was established, and the data analysis methods including fracture toughness calculation, datum censoring and reference temperature T₀ calculation of W-shaped specimen were determined, after referring to ASTM E1921 standard. Finally, W-shaped specimen and 1C(T) specimens of domestic A508-Ⅲ steel were tested at -100--40 ℃, the results were used to validate the effectiveness of the W-shaped specimen test data. The results show that effective fracture toughness data determined by ASTM E1921 can be obtained based on the W-shaped specimen. The test data of W-shaped specimens are all within the confidence interval of the master curve determined by 1C(T) specimen. T₀ determined by the W-shaped specimen is very close to that of standard 1C(T) specimen. The W-shaped specimen can be applied as the candidate fracture toughness specimen of RPV surveillance program.