对运行10 a的3Cr1Mo1/4V钢制加氢反应器内试块取样进行了脱脆热处理，与未热处理（脆化态）试样在不同温度下进行了小冲杆试验和夏比冲击试验，提出了以断裂能与最大载荷的比值（E_SP/F_m）作为确定小冲杆试验韧脆转变温度的方法，得到韧脆转变温度及其增量，并与夏比冲击试验结果进行了对比。结果表明：小冲杆试验得到的E_SP/F_m-温度曲线与夏比冲击试验得到的冲击功-温度曲线具有相同的变化趋势；与断裂能相比，E_SP/F_m可以更好地表征材料的韧脆状态；以E_SP/F_m稳定值的60%对应的温度作为韧脆转变温度，得到的韧脆转变温度增量与由夏比冲击试验得到的近似相等，小冲杆试验可以用来评价3Cr1Mo1/4V钢的回火脆性。

The de-embrittlement heat treatment was conducted on specimens sampled from the tested block in a 3Cr1Mo1/4V steel hydrogenation reactor, which had runned for 10 a. And the small punch test and Charpy impact test were carried out on the de-embrittled specimens and non-heat treated (namely embrittled) specimens at different temperatures. A method using the ratio of fracture energy to maximum load (E_SP/F_m) to determine the ductile-brittle transition temperature of small puch test was proposed. The ductile-brittle transition temperatures and the increments were obtained and compared with those from Charpy impact test. The results show that the changing trend of E_SP/F_m-temperature curves obtained from small punch test had the same trend as the impact energy-temperature curves from Charpy impact test. Comparing to the fracture energy, E_SP/F_m can present the ductile to brittle state better. Using the temperature corresponding to 60% of stabilized E_SP/F_m as the ductile-brittle transition temperature, the obtained ductile-brittle transition temperature increment was nearly equal to that obtained by Charpy impact test. The small punch test can evaluate the temper-embrittlement of 3Cr1Mo1/4V steel.