The invention provides a minute spherical Nd-Fe-B powder preparation method, belonging to the powder preparation technical field. The method combines the hydrogen decrepitation (HD) technology with the radio frequency (RF) plasma melting and spheroidizing technology, selects hydrogen absorbing Nd-Fe-B powder as the raw material, completes the steps of hydrogen decrepitation, dehydrogenization and titanium powder spheroidization of the hydrogen absorbing Nd-Fe-B powder simultaneously by plasma treatment and prepares minute spherical Nd-Fe-B powder. The invention has the advantages that the method combines the hydrogen decrepitation (HD) technology with the radio frequency (RF) plasma melting and spheroidizing technology, shortening the technological process of production, improving the production efficiency, reducing the production cost, and guaranteeing that the prepared spherical Nd-Fe-B powder has minute granularity, even ingredient, good fluidity, high sphericity and low oxygen content and meets the demand for bonding Nd-Fe-B permanent magnet in industrial production.