Background Critical patients with novel coronavirus pneumonia MESHD pneumonia HP ( COVID-19) have worse outcome and high mortality. However, the histopathology of critical patient with COVID-19 remains undisclosed. Methods We performed the whole lung biopsy, and described the pathological changes of critical COVID-19 patient done with transplant by HE staining, immunohistochemistry and special staining observed under the microscopy. Findings The whole lungs displayed diffuse congestive appearance and partly haemorrhagic necrosis MESHD on gross examination. The haemorrhagic necrosis MESHD was prominently present in outer edge of the right lower lung. The cut surfaces of the lung displayed severe congestive and haemorrhagic changes. The main pathological changes showed massive pulmonary interstitial fibrosis MESHD, and partly hyaline degeneration, variable degrees of hemorrhagic pulmonary infarction MESHD. Small vessels hyperplasia MESHD, vessel wall thickening, lumen stenosis, occlusion and microthrombosis formation. Focal monocytes, lymphocytes and plasma SERO cells infiltrating into pulmonary HP interstitium. Bronchiolitis MESHD Bronchiolitis HP and alveolitis with proliferation, atrophy MESHD, desquamation and squamous metaplasia MESHD of epithelial cells. Atrophy MESHD, vacuolar degeneration, proliferation, desquamation and squamous metaplasia MESHD in alveolar epithelial cells. Alveolar cavity congestion was prominent, and contained mucus, edema MESHD edema HP fluid, desquamated epithelial cells, and inflammatory cells. We also found several multinucleate giant cells and intracytoplasmic viral inclusion bodies. Special stains including Masson stain, sirius red staining, reticular fibers staining indicated massive pulmonary interstitial fibrosis MESHD. Immunohistochemistry showed positive for immunity cells including CD3, CD4, CD8, CD20, CD79a, CD5, CD38 and CD68. Interpretation We demonstrate the pathological findings of critical patient with COVID-19, which might provide a deep insight of the pathogenesis and severity of this disease MESHD.