Objective To evaluate the staining defects of Masson trichrome staining, and analyze the main causes and solutions. Methods Five paraffin specimens of nodular liver cirrhosis diagnosed by pathology were selected in 2020 from Department of Pathology, The Third Affiliated Hospital of Naval Medical University (Second Military Medical University). They were consecutively sectioned into 4 μm slices, and then the slices were distributed to all the participating hospitals for Masson trichrome staining. The stained slices were scored by 2 physicians according to the scoring standard, and then they were graded by average score. Results In this Masson trichrome staining inter-laboratory quality control evaluation, a total of 50 slices were distributed, and finally 48 hospitals submitted stained slices (48 slices), including 17 in grade A, 25 in grade B, 4 in grade C, and 2 in grade D. The staining defects mainly included:light staining of nucleus, poor contrast with cytoplasm; the nuclei were stained too dark and fuzzy, and the cytoplasm was gray blue; the cytoplasm was stained too dark or too pale; the smooth muscle fibers was not stained or gray rather than red; and the tissue structure showed false staining or uneven staining, such as the collagen was not stained or the whole section was stained blue. Conclusion It is necessary to strictly control the staining temperature, staining time, pH value, reagent preparation and preservation and other relevant details in the staining process of Masson trichrome staining, so as to ensure the quality of trichrome staining and the stability and reliability of staining.