Abstract: A measuring method of peak field grandient of pulsed quadrupole magnets isdescribed. A pair of coils for grandient, an integrater and measuring circuit ofpeak voltage are used in this measuements. It is used for field measurementsof drift tube quadrupole magnets in proton Linac. It's accuracy is 0.3%,The excitation curves of two type of drift tube quadrupole magnets are givenand compared with theory.