The invention discloses a high-strength heat-resistant steel gas-shielded solid wire. The solid wire comprises, by mass, 0.10-0.15% of C, 1.75-2.20% of Mn, 0.85-0.95% of Si, S<=0.015%, P<=0.015%, Cu<=0.20%, 0.30-0.60% of Cr, 1.50-2.50% of Ni, 1,40-1,50% of Mo, 0.05-0.20% of V, 0.02-0.05% of Ti, 0.05-0.15% of Al, 0.04-0.20% of Nb and the balance Fe. Deposited metal and welded joints obtained through the wire can reduce embrittlement during long-term usage and are provided with good comprehensive performance, structure stability, heat resistance and good strengthens and toughness matching of high-strength steel structures are provided, good welding processing properties are provided, the wire feeding is smooth, splashing is small during a welding process, and the molding is attractive in appearance; the solid wire is particularly suitable for welding pressure vessels with heat resistance and toughness requirements; and the comprehensive performance of the obtained deposited metal includes: the yield strength>=600MPa, the tensile strength>=700MPa, the elongation>=20%, and the impact toughness Akv>=60J under the room temperature condition.