Abstract: The definition and clinical classification of pulmonary hypertension (PH) were updated in the 6th World Symposium on Pulmonary Hypertension (WSPH). The hemodynamic definition of PH keeps no change, but pre-capillary PH was redefined as mean pulmonary arterial pressure>20 mm Hg, pulmonary artery wedge pressure < 15 mm Hg and pulmonary vessel resistance>3 WU. The updated clinical classification included:pulmonary arterial hypertension(PAH) with vasoreactivity was added as a subclass of PAH; in drugs and toxins induced PAH, the role of methamphetamines and dasatinib was updated from likely to definite; pulmonary veno-occlusive disease/pulmonary capillary haemangiomatosis was changed from 1' to a subclass of PAH; splenectomy and thyroid diseases were withdrawn from the group 5 of PH, etc. These clinical practice updates will guide clinical practice better.