In order to find out the drought threshold of maize in different growth periods under the condition of no tillage under straw mulching, so as to scientifically guide supplementary irrigation and avoid water resource waste. Our team conducted drought experiments with different gradients in the artificial awning from 2018 to 2019. The results showed that,?with 5% reduction as the critical point, the drought threshold under no-tillage coverage was 0.609 during the period from jointing to tasseling, which was significantly higher than 0.551 under the condition of open rotary tillage, but there was no significant difference between tasseling and milk ripening (0.524 and 0.512, respectively). In terms of the time of occurrence of drought threshold, the coverage was 6.1 days later than that of bare land during jointing to tasseling, but the difference was reduced to 3.7 days between tasseling and milk ripening. These results indicated that straw mulching could significantly improve the drought resistance of maize and extend the interval of necessary water replenishment (especially from jointing to tasseling), so as to reduce the number of water replenishment during the whole growth period of maize with the same yield.