In recent years, nanobubbles (NBs) as a novel technology have attracted people’s great concern in both agricultural and engineering fields. It has been proved that the water contain-ing NBs can accelerate the growth of plants, shellfish and yeast. Up to now, the explanation has not theoretically been given for these new scientific findings, especially to growth promo-tion and sterilization. On the other hand it is known that reactive oxygen species (ROS) play a vital role in growth by facilitating the required cell wall loosening for cell elongation. In our latest research we’ve reported that the water containing NBs can produce hydroxyl radicals in the water. Here, we’ve reported a direct evidence for the positive effect of NBs on the ROS production inside barley seeds.