The invention relates to a spinning forming method of a stainless steel seamless pipe with a flange at an end. The method comprises the following steps of: firstly, manufacturing a mold comprising a core mold, rotating wheels and a tail top; designing a boss on the end portion of the core mold; uniformly distributing a plurality of keyways on the boss; mounting four uniformly distributed rotating wheels on a spinning device, wherein opposite two rotating wheels are located on a same plane, and two adjacent rotating wheels are distributed alternately along axial and radial directions; then processing a stainless steel cylindrical blank, processing an inner convex step on the tail portion of the blank, and processing through slots in the inner convex step, wherein the inner convex step is matched with the boss on the end portion of the core mold, and the through slots correspond to the keyways in the mold one by one; placing a key block in each through slot and the corresponding keyway, fixing the key block and the core mold, and leaning against the core mold with the tail top; and controlling a main shaft to rotate by means of the spinning device and controlling the rotating wheels to extrude the blank to realize seamless spinning and forming of the stainless steel seamless pipe. The method provided by the invention increases the forming quality, precision and reliability, can manufacture stainless steel straight pipes which are different in wall thickness, and improves the optimizing margin of a structural design.