The invention belongs to the technical field of spatial traveling wave tube nonlinearity, and particularly relates to a clamping rod adjustment-based spatial traveling wave tube group time delay inhibition method. According to the method, a synchronous deviation of an electron beam and an electromagnetic wave is controlled by adjusting the width n of a rectangular clamping rod of a first interaction section, and a relative phase angle of the first interaction section is enabled to be about 50 degrees, so that the group time delay is greatly inhibited by consuming a small amount of output power, the fluctuation cycle is greatly shortened, and the fluctuation range is greatly narrowed. On the premise of ensuring that the output power meets a user index (>150W) in the whole frequency band range, the group time delay is remarkably inhibited, and the fluctuation range and the fluctuation cycle are remarkably narrowed and shortened; and the method mainly aims at spatial traveling wave tubes used for communication.