The invention discloses a method for diagnosing false oil level of an oil-immersed type power transformer based on three vibration sensors, which solves the problem of monitoring failure of the oil level of the running oil-immersed type power transformer by the existing oil level meter. The method is characterized in that an oil level test box (5) is arranged on the plane of the outer side of a transformer oil conservator (3); a vibration sensor mounting base (7) is movably arranged on the oil level test box (5) at one side of an oil level measuring dial gauge (17), an electromagnet (21) is arranged on the vibration sensor mounting base (7), and a coil (16) of the electromagnet (21) is electrically connected with an electric controller (11); a first spring (19) is arranged on the vibration sensor mounting base (7), the outer end of the first spring (19) is connected with a first vibration sensor (14), and the first vibration sensor (14) is electrically connected with a vibration frequency monitor (10) through a signal transmitting line (9). The method is used for testing and diagnosing under the condition of no power interruption of the transformer.