Pentacyclic triterpenoids are an important class of natural organic compounds that are abundant and widely distributed in nature,with a variety of biological activities such as anti-tumour,anti-diabetic,anti-viral,anti-oxidant and anti-bacterial.Structural modification of pentacyclic triterpenoids by biotransformation technology can provide more lead compounds with novel structures for bioactivity screening,and thus lay the foundation for the development of new pentacyclic triterpenoids with greater bioactivity.In this paper,the five most representative compounds of the three structural types of pentacyclic triterpenoids (oleanolane-type,ursane-type and lupinane-type),namely oleanolic acid,glycyrrhetinic acid,glycyrrhizic acid,ursolic acid and betulinic acid,are reviewed in the last 10 years of biotransformation research results to provide reference for natural product biotransformation research and new drug development.