The present invention pertains to the field of pharmaceuticals, and relates to an application of cannabidiol (CBD) in the treatment of pulmonary hypertension. The cannabidiol can be used as a sole active ingredient or in combination with other active ingredients to prepare a medicament for treating pulmonary hypertension. Specifically, the present invention relates to a use of any one of the following (1) to (3) for the preparation of a medicament for the treatment and/or prevention of pulmonary hypertension : (1) cannabinol, (2) a plant extract containing cannabidiol, wherein preferably, the plant extract is a cannabis extract, and (3) a pharmaceutical composition containing cannabidiol and one or more pharmaceutically acceptable excipients. Experimental research of the present invention has revealed an effect of cannabidiol of inhibiting pulmonary hypertension, and the invention is particularly suitable for the treatment of pulmonary hypertension caused by hypoxemia.