Flow cytometry (FCM) uses flow cytometer to detect the expression of immunological markers on cells based on antigen-antibody binding and laser activating fluorescence. FCM plays a very important role in clinical diagnosis especially in acute leukemia diagnosis and subclassification. However, due to the difficulty in acquiring the sample and the existence of normal lymphocytes in the background, its application and improvement should be further strengthened in the diagnosis of mature lymphoid neoplasm. This paper focuses on the similarity and differences between FCM and pathology immunohistology, immune makers in lymphoma detection, immunophenotypic features of common mature lymphoid neoplasm, common issues and key points in FCM detection, to study the diagnostic application of flow cytometry in mature lymphoid neoplasm. This will help clinicians understand this technic, and make a correct diagnosis by FCM combining with pathology.