Abstract: Low temperature brittle fracture resistance of asymmetrical synchronous double-sided arc welded (DSAW) joint of 10Ni5CrMoV steel was investigated by series temperature impact test, dynamic tear test and drop hammer test. The results show that DSAW joints of steel 10Ni5CrMoV have a practicable brittle fracture resistance. The impact energy value on the fusion line of DSAW joint meets the technical requirement of the 10Ni5CrMoV steel (i.e., Akv(-50℃≥47 J) with a large allowance. Minimum of dynamic tearing energy at -1℃ is 1150 J, higher than the standard of 644 J DT work at 0℃. Drop hammer test determines that the nil-ductility transition temperature of weld metal of 10Ni5CrMoV steel is -80℃, elastic fracture transition temperature is -47℃, full plastic fracture transition temperature is -14℃.