Objective To explore the imaging features of acute exacerbation of idiopathic pulmonary fibrosis ( IPF) under high-resolution computed tomography ( HRCT) . Methods The HRCT imaging features of six patients who met the criteria for acute exacerbation of IPF were analyzed retrospectively. Results The manifestations of IPF on HRCT scan were various in forms and distribution, as multifocal, ground-glass opacity, reticular shadow, honeycombing densities, capillary bronchiectasis,subpleural lines, traction bronchiolectasis and emphysema. The characteristic lesions were newly diffuse bilateral ground-glass opacity at the time of acute exacerbation, superimposed on subpleural reticular and honeycombing densities. Conclusions Chest HRCT findings in acute exacerbation of IPF are characteristic.HRCT is accurate and superior in diagnosis of IPF and in determining acute exacerbation of IPF.