A generator stator center adjusting device belongs to the technical field of generator equipment installation tools and is used for adjusting the center position of a generator stator. According to the technical scheme, stator center adjusting plates are fixedly connected to the two sides of a stator bedplate respectively, adjusting bolts penetrate through screw holes of the stator center adjusting plates to be opposite to the two sides of a stator respectively, the adjusting bolts are matched through feeler gauges to transversely move the stator, and therefore the purpose of adjusting the center position of the stator is achieved; Meanwhile, the gap between the stator and the rotor is detected through the air gap measuring block, and then the gap between the stator and the rotor is adjusted through the stator center adjusting plate and the adjusting bolt to reach the average value of the air gap within 10%. The steam turbine generator stator center adjusting device is simple to manufacture, convenient to operate, not limited by conditions and high in universality, solves the problems that in the equipment installation process, the steam turbine generator stator center adjusting amount is small, and the force is not easy to control, avoids damage to the generator stator, saves installation and maintenance time, and greatly reduces the labor intensity of workers.