Curcumin is a kind of diphenylheptane compound， which has been widely studied because of its evidenced health benefiting effects. However， due to the poor bioavailability of curcumin after digestion and absorption， the mechanisms underlying its bioefficacy have been controversial. This paper reviewd the research progress on the absorption， transportation and metabolism of curcumin in vivo. Curcumin mainly experiences the reduction and conjugation reactions when absorbed through the upper gastrointestinal tract and participates in metabolic pathways where characteristic metabolites such as tetrahydrocurcumin， hexahydrocurcumin， curcumin glucuronide， sulfated curcumin are produced. Its metabolic process in the lower gastrointestinal tract has become the research hotspot in recent years. Curcumin can not only be metabolized into highly active metabolites by gut microbiota， but can also regulate the profile of gut microbiota and maintain the homeostasis of gut microbiota. The absorption and metabolism of curcumin and its bidirectional interaction with the gut microbiota are critical in unveiling the contradiction between the health effect of curcumin and its low bioavailability.