Abstract: Frequency veering in a bladed disk is the result of system mode interaction,which will greatly affect the vibrational characteristics of the system.In view of system modal power,the expressions of various sub-mode powers were derived from the eigenfunction of a bladed disk in this paper.By using a lumped parameter model,the characteristics of frequency veering and variations of sub-mode powers were systematically investigated.While studying comprehensively the variation features of the mode interaction power of the bladed disk,the interaction between frequency veering and variations of sub-mode powers was thoroughly analyzed and summarized.This method and conclusion could provide a fundamental theory for looking into the physical insight of frequency veering of a bladed disk.