The invention relates to a method for preparing a test real object for a G3 alloy oil well pipe by welding, which is used for preparing oil-drilling oil pipes or casing pipes and chucks made of 35CrMo or 30CrMo materials by welding. The invention is characterized in that the method comprises the following steps: weldment preparation; preparation of a welding device and a welding electrode; preheating a workpiece before welding; and adopting the welding electrode with a diameter of 3.2 cm, selecting a principle for the welding parameter with proper current, low electric arc as much as possibleand recommended welding current of 90-120 A, and controlling the range of energy of a weld line within 0.5-1.0 kJ/mm; performing rendering by using a stainless steel electrode, performing full penetration of welding to the root part, uniformizing girth welding into 4-5 layers, then performing welding by using a double-phase stainless steel electrode, performing uniform girth welding, providing atleast 3-4 mm of height of reinforcement for the welding seam after completely welding an end bevel, and performing built up welding on the edge of a welding seam of a test pipe to obtain two welding seams; and covering the welding seams with heat insulation material to cool after finishing welding. The invention has the effects that the welding joint is intact, the welding process is feasible after certification, and the problem of connection between the G3 alloy oil well pipe and the chuck during the real object test is solved.