Pulmonary drug delivery systems (PDDS) have gained particular attention by pharmaceutical scientists due to its potent in the therapy of both pulmonary diseases and systemic diseases. Metered dose inhalers (MDI) as a delivery approach of PDDS have ample advantages over other approaches. No drying process is associated with MDI, which avoids the chemical and physical instability. MDI are cost-effective, portable and can be self-administered. It was recently reported that MDI had occupied a large proportion of the respiratory drug market since the last century. To facilitate the future studies on MDI, this work was aimed to conduct bibliometric analysis of the publications of MDI in Science Citation Index Expanded database of Web of Science from 2000 to 2020 (2,858 in total). The documents were processed by Clarivate Analytic tool equipped by Web of Science, VOSviewer, Statistical Analysis Toolkit for Informetric (SATI) and bibliometric online platform, and the data were visualized. After describing the detailed bibliometric profile of MDI publications, which included publication years, countries/regions, organizations, research areas, publication media, authorship and funding agencies, we assessed the publication tendencies by virtue of analysis of co-citation, bibliographic coupling, keywords and co-occurrence. Based on the results, we put forward three promising topics for future studies of MDI. Taken together, we believed that MDI had become a topic under investigation across the world, and will still be an emphasis for fundamental and translational researches.