A method for preparing organoboron derivatives containing oxygen atoms and an aromatic ring as labeled precursors of dopamine positron emission tomography imaging agents is revealed. Hydrochloride salt of cocaine is used as an initiator. Organoboron derivatives containing oxygen atoms are directly produced on an aromatic ring as drug substances and the aromatic ring is directly labeled with radioisotope fluorine-18 (F-18). The method takes only five steps including four steps for preparing organoboron derivatives containing oxygen atoms and an aromatic ring as drug substances and a step of labeling the aromatic ring of the organoboron derivatives with F-18 directly. Not only the process time is significantly reduced, the total yield rate is also improved effectively.