The purpose of tempering is to change the moisture content of wheat and improve the processing quality of grain. Three kinds of representative domestic wheat (soft, medium and hard) were used as experimental materials, and the temperature gradient was set, and the water state change under different conditions was studied by using low-field nuclear magnetic resonance (NMR) technology; the water migration patterns under different conditions were studied by nuclear magnetic resonance imaging (NMRI).The results showed that: T21 and A21 of the samples showed a significant upward trend under different tempering temperature; T22, A22 first decreased and then increased; T23 was positively correlated with temperature, and A23 reached the peak at the preliminary stage of tempering then decreased gradually. NMRI showed that there were two major pathways of moisture and one ancillary path in wheat kernel. One was moisture diffused through the nucellar layer into the germ line, the other was moisture infiltrated through the cell wall of the aleurone layer; the auxiliary path was moisture diffused from the fuzzy end to the endosperm center.