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Putting forward easilyobserved and operate rice watersaving irrigation regulation indicators is of great significance to promote the largescale application of rice watersaving irrigation technology. The method of pot experiment and model scenario simulation (Hydrus-1d) was used to study the variation of soil moisture and the depth of saturated soil during the drying and dehydration of paddy fields under different water intensities. The quantitative relationship between the soil moisture and the depth of saturated soil were established. The results show that the soil moisture and the depth of saturated soil during the paddy field dehydration had a good synchronous change law. The correlation coefficient between the measured soil moisture and the simulated soil moisture was 0.758 by using the Hydrus-1d model, which can better simulate the synchronous change of the two in the process of rice field dehydration. Both the experiment and the simulation results showed that there was a clear quadratic parabolic relationship between the soil moisture and the depth of saturated soil in the watersaving irrigation paddy field, that was, the depth of saturated soil was increased with the decrease of soil moisture in the process of rice field dehydration. In addition, based on the quantitative relationship between the two and the traditional critical value of soil moisture index, the critical value of the depth of saturated soil index was calculated, and the critical value of saturated soil depth in each growth period was ranged from 0.27m to 0.50m, forming a watersaving irrigation technology of rice with saturated soil depth as the control index. The technology used easilyobserved depth of saturated soil as a control index, which overcame the problems of high monitoring cost and low measurement accuracy brought by using the soil moisture and a fixed number of days in an anhydrous layer as the control index, accurately reflecting the field moisture status, and at the same time, it met the needs of largescale application of watersaving irrigation.