The invention relates to a detection method for familial defects of power equipment of a power supply plant. The method comprises the following steps of S1, endowing equipment in a power generation system with KKS codes respectively, and obtaining historical defect records of the equipment in the power generation system from a database; S2, according to the historical defect records of the equipment in the database, calculating a defect rate threshold d0 of the equipment; S3, according to serial numbers, types and manufacturers of the equipment, obtaining a classification matrix of the equipment; S4, comparing the values of d1, d2, ..., dM, and defining the equipment manufacturer with the defect rate value greater than the defect rate threshold d0 as the equipment manufacturer with the familial defects; S5, calculating a correlation coefficient r between the equipment manufacturer with the familial defects and the defect rate of the equipment, and when r is greater than a critical value r0, determining that the equipment manufacturer really has the familial defects; and S6, taking the KKS code of the equipment corresponding to the defect with the correlation higher than a familialdefect judgment threshold as the KKS code of the equipment with the familial defects, and calculating the defect rate df of the equipment manufacturer with the familial defects.