The incidence of idiopathic pulmonary fibrosis complicated with lung cancer(IPF-LC)has been rising,however,the pathogenic mechanism of IPF-LC is not clear.IPF is an independent risk factor for lung cancer,while there are partially overlapped risk factors and common molecular targets for these two conditions.It is facing difficulties to diagnose and treat IPF-LC,and even some anti-tumor treatments may lead to acute exacerbations of IPF and even death of patients,which makes a poor prognosis of IPF-LC patients.Therefore,it is necessary to explore new diagnostic methods and develop appropriate treatment plans for IPF-LC.This article reviews the epidemiology,pathogenesis and difficulties in diagnosis and treatment of IPF-LC.