The present application discloses a method and system for generating a liquid containing nanoscale bubbles. The method is as below: a liquid is introduced into a pressure vessel containing gas throughan atomizing nozzle, the liquid forms droplets in the pressure vessel, and the gas diffuses into the droplets at a pressure higher than atmospheric pressure; then the gas-containing liquid in the pressure vessel is sent to a narrow space, and the size of at least one dimension of the space is less than 20 mm; and finally, the gas-containing liquid is sprayed from a narrow space into an open environment with a pressure below that of a narrow space.