The invention discloses a working method of a good-performance large transformer bell housing indoor on-site vertical lifting device. The working method is characterized in that a main machine of a control system transmits a command, and a left pneumatic cylinder and a right pneumatic cylinder work; the left and right pneumatic cylinders drive left and right double-shear fork lifting devices; cross beams are driven to rise, and the cross beams lift a transformer bell housing through lifting hooks; whether the lifting heights of the left and right double-shear fork lifting devices on two sides of the cross beams are consistent or not is detected by adopting displacement sensors, and feedback is given in real time; if an error exists, the control system is used for adjustment, so that synchronous operation of lifting heights of two sides is realized; and the balance of a lifted object during a lifting process is ensured. According to the transformer lifting device, the double-shear fork-type gantry structure is adopted, so that the maximum lifting height can reach 8 meters, and the maximum lifting weight can reach 10 tons.