The invention discloses a power system fault diagnosis method comprehensively using electricity amount and timing sequence information. Firstly, power-off areas before and after a fault are compared and analyzed to determine the fault area, and a suspicious element set is formed; secondly, a weighting fuzzy timing sequence Petri net model is built, and SCADA information, electricity amount information of a WAMS and the timing sequence characteristics included in the information are integrated to form the alarm information criterion, place delay restraints and the electricity amount criterion; a Gaussian function is adopted, the confidence coefficient of alarm information is obtained in combination with timing sequence reasoning, the initial confidence coefficient of the Petri net model is calculated through array calculation, and the model is solved; finally, backward reasoning is carried out according to the fault probability of an element, and protection and judgment of maloperation and motion refusal of a disconnector are carried out. The power system fault diagnosis method is high in fault-tolerant capability, can handle the phenomena of protection and maloperation/motion refusal of the disconnector and the phenomenon that an alarm is lost or wrong, and improves the accuracy and reliability of the fault diagnosis result.