With the vigorous development of power electronization in distribution network

harmonics in power grid gradually extend toward high frequency and ultrahigh harmonics（2～150 kHz） have become a new type of power quality problem that cannot be ignored.Accurate measurement is the base of studying ultrahigh harmonic.However

the present measurement method is no longer applicable due to the limit traditional harmonic measurement theory system.In this paper

the generating mechanism of ultrahigh harmonics of power electronic converter is analyzed briefly and

from the perspective of relevance of fundamental frequency

the difference between harmonic and ultrahigh harmonics is compared.On this basis

the applicability of harmonic measurement method stipulated in GB/T 17626.7 to ultrahigh harmonics is discussed.Then

a general method of harmonic and ultrahigh harmonics measurement using different harmonic grouping methods under equal interval synchronous sampling mode is proposed to achieve compatibility between the two methods

and the rationality of the measurement method is verified by the simulation and measured data.It provides a basis for the research of ultra-highharmonics propagation characteristics

compatibility level and evaluation of harnessing effect.