As a medicinal and edible fungus, Inonotus obliquus has a long history of folk application in Russia, Japan, and Northeast China. It is rich in terpenoids, steroids, polysaccharides, phenols, alkaloids, etc, and exhibits pharmacological activities including anti-tumor, hypoglycemic, anti-inflammatory, antioxidant, and lipid-lowering effects. Among these, lanostane-type tetracyclic triterpenes represent its characteristic constituents. This review systematically summarizes the research progress on the chemical components isolated and identified from I. obliquus and their pharmacological activities in recent years. The structures of terpenoids, steroids, and phenolic compounds are compiled and illustrated, with a particular focus on the skeletal types and structural characteristics of lanostane-type tetracyclic triterpenes. This work aims to provide some reference for the further investigation and comprehensive development and utilization of I. obliquus.