The invention discloses a method and system for detecting the state of a power distribution transformer under harmonic load influence. The method includes the following steps that: the noise signals of the power distribution transformer are detected; a noise signal characteristic parameter and a sound pressure level are extracted; and the noise signal characteristic parameter is compared with a preset noise signal characteristic parameter threshold value, if the noise signal characteristic parameter is higher than the preset noise signal characteristic parameter threshold value, it is judged that the power distribution transformer is in a harmonic load operating state, and the sound pressure level is compared with a preset sound pressure level early warning threshold value, if the sound pressure level exceeds the preset sound pressure level early warning threshold value, it is judged that the operation of the power distribution transformer is abnormal, otherwise, it is judged that the operation of the power distribution transformer is normal. The system comprises a noise signal detection program unit, a noise characteristic extraction program unit and a state detection program unit. According to the method and system of the invention, contact with electrified equipment is not required, so that the safety of detection is high; workers are not required to go to a site to carry out detection and analysis; and therefore, the method and system of the invention have the advantages of time-saving and labor-saving performance, high safety, high efficiency and convenient detection.