The invention relates to a reverse bubble generator and a preparation method. According to the reverse bubble preparation method, a dispersed-phase jet flow or liquid droplet is generated from a first fluid through gas phase; and under the action of external force, the jet flow or liquid droplet moves to a second fluid in a continuous phase through a liquid membrane, and reverse bubbles are formed. According to the reverse bubble generator and the preparation method, a large quantity of reverse bubbles is generated simply and conveniently, and demand of large-scale industrial application can be met.