Abstract: Effect of interpass temperature on mechanical property of 10CrNi5MoV steel gas shielded welding joint was investigated in two different energy input by yield strength, impact toughness testing and tissue analysis. The results indicated that when the energy input was 8 kJ/cm and 18 kJ/cm, the yield strength of weld metal monotonic decreased from 868 MPa and 855 MPa to 728 MPa and 693 MPa respectively, impact toughness at- 50℃ of weld metal rised from 70 J and 69 J to 117 J and 72 J(interpass temperature was 200℃ and 100℃ respectively), then reduced to 67 J and 43 J. The difference in the tissue made the mechanical property changed with the interpass temperature elevated. With interpass temperature rised from 40℃ to 300℃, the content of martensite structure in weld metal gradually disappeared, granular bainite structure gradually increased, acicular ferrite structure increased first, and then decreased. The interpass temperature corresponded to the peak of acicular ferrite structure content was consistent to the peak of the impact toughness.