The invention discloses a hoisting process for a large flare stack of a floating production storage and offloading (FPSO) ship. The hoisting process comprises the steps that S1, a main hanging beam and an auxiliary hanging beam used for hoisting the flare stack are built in the position 66500 mm high of the flare stack and the position 27500 mm high of the flare stack correspondingly; S2, before the flare stack is hoisted, three guide limiting devices are installed on a ship bow deck; and S3, the whole flare stack is hoisted, a first lifting hook is lifted to enable a stack body of the flare stack to incline by 70 degrees, and three stand columns of the flare stack are installed on the corresponding guide limiting devices. The hoisting process for the large flare stack of the FPSO ship is an overall one-time hoisting process, and the hoisting cost is low; in the hoisting process, the stack body inclines by 70 degrees so as to ensure that the center of gravity of the flare stack is kept between the main hanging beam and the auxiliary hanging beam, and the stack body of the flare stack is not prone to swinging and prevented from being collided with other modules; and the main hanging beam and the auxiliary hanging beam are welded to the flare stack and clamp the stack body of the flare stack, so that the flare stack is protected against structural deformation in the hoisting process, and the guide limiting devices ensure the installation precision.