The invention relates to a submerged-arc welding flux with high-strength, high-tenacity and high-welding-speed used in high grade pipeline steel, which comprises the following components in mass percentages: 32-40 portions of MgO, 20-25 portions of Al2O3, 15-25 portions of SiO2, 15-25 portions of CaF2, 3-8 portions of rare earth oxide, the contents of S is less than 0.04, the contents of P is less than 0.04. The invention meets the requirements of high welding speed high strength and high tenacity for X80 grade steel welding seem by adjusting the contents of MgO, Al2O3 and so on in the welding flux and adding rare earth oxide to the welding flux as well. The invention matches with H80 welding wire, which ensures that the weld metal has high strength and tenacity and good processing properties.