Abstract: In order to resolve the problem of low irrigation uniformity of rainwater harvesting and gravitational irrigation systems, this study advanced a new method that could increase the irrigation uniformity of low water head gravitational irrigation: underground bottle irrigation, demonstrated the principle of this method, and conducted a preliminary research on the underground step of this method in air dried, loose soil. The results showed that: underground bottle irrigation could form an ellipsoidal wet soil body which had relatively even distributed soil water content around the bottle. 1-2 days after 5 L water was irrigated, water spread horizontally to 10-15 cm from the bottle and vertically to 16-23 cm from bottom of the bottle. The average water content in the wet soil body was about 17%. The irrigation water wouldn’t percolate to deep soil layers. Moreover, the characteristics of the wet soil body and the dill method of irrigation bottle were not well related, which was convenient for arrangement of irrigation bottles in field. The underground bottle irrigation was a simple and feasible method which would be commonly used in the semi-arid loess hilly regions.