The invention relates to an extrusion deformation technology for large-diameter high-strength heat resistant magnesium alloy pipes. The alloy comprises the following components in percentage by weight: 6 to 13 percent of Gd, 2 to 6 percent of Y, 0.3 to 0.8 percent of Zr and the balance of Mg. The technology comprises the following steps of: preparing a magnesium alloy ingot blank by a semi-continuous casting method, performing saw cutting, homogenization and air cooing on the ingot blank, peeling, heating, preserving the heat and extruding, wherein the temperature of the bank is 400 to 405 DEG C and the temperature of an extrusion die is 380 to 385 DEG C; and finally, performing isothermal aging at the temperature of between 205 and 215 DEG C for 30 to 50 hours. The outside diameter of the obtained pipes is 40 to 70 millimeters, and the wall thickness of the pipes is 3 to 6.5 millimeters. The pipes have the mechanical properties that: at the extrusion state room temperature, the tensile strength is more than or equal to 340MPa, the yield strength is more than or equal to 240MPa, and the elongation rate is more than or equal to 13.6 percent; at the T5 state (extrusion and aging) room temperature, the tensile strength is more than or equal to 420MPa, the yield strength is more than or equal to 318MPa, and the elongation rate is more than or equal to 3 percent; at the temperatureof 250 DEG C, the tensile strength is more than or equal to 320MPa, and the elongation rate is more than or equal to 12 percent; at the temperature of 300 DEG C, the tensile strength is more than or equal to 230MPa, and the elongation rate is more than or equal to 20 percent; and at the temperature of 350 DEG C, the tensile strength is more than or equal to 100MPa, and the elongation rate is morethan or equal to 45 percent.