The invention discloses a method for measuring unbalance amount of a rigid rotor by using static balance. The method comprises the steps of detecting an unbalanced direction of the rigid rotor on a statically-balanced rack, detecting a swinging period of the rigid rotor on the statically-balanced rack and determining the unbalance amount of the rigid rotor. A simple and reliable static balance measurement method for measuring the unbalance amount of the rigid rotor and evaluating the balance quality is provided. By the method, the unbalance amount and the unbalance direction of the rigid rotor can be determined effectively; the problem that the measurement on the unbalance amount of the rigid rotor by using the static balance measurement method cannot be evaluated quantitatively is solved, so the one-time correcting rate during the balance correction of the rigid rotor is more than 90 percent; the requirement on the balance correction of the rotor by using the static balance measurement method is to ensure the rest unbalance amount of the rotor is less than the available unbalance amount of the rotor rather than ensure the arbitrary balance of the whole balance system; and therefore, the time for the balance correction of the rotor is greatly shortened from two aspects and the efficiency and effectiveness of the balance correction of the rotor are improved.