The invention provides a method for improving the vibration monitoring precision of a rotor aeroengine, and the method employs a calculated sampling frequency for the continuous collection of a signal, wherein the collection length is a calculated period number, thereby achieving a purpose of the full-period collection of two or three fundamental frequencies, so as to guarantee the precision of the subsequent data processing. The method employs a dynamic optimization sampling rate and collection point number method, tries to avoid the frequency spectrum leakage of the fundamental frequencies of all rotors at the same time, and improves the amplitude testing precision. Therefore, the method can increase the effective information amount in a vibration signal, and provides technological basis for reducing the number of airborne sensors. The method can remarkably reduce collection precision of the fundamental frequencies of all rotors, guarantees the normal operation of an engine, provides the technological basis for the fault diagnosis of the engine and the onsite dynamic balance, and provides technological support for the health management of the engine.