Objective: To investigate the application values of non-invasive skin barrier function detection in Langerhans cell histiocytosis (LCH). Methods: From January 2017 to December 2020,72 cases of patients with Langerhans cell histiocytosis treated in our hospital were selected as the LCH group, and the other 72 cases of health examination were selected as the control group during the same period. The non-invasive skin barrier function were used to detect skin moisture, transdermal water loss (TEWL) and oil levels. At the same time, the immune function and skin flora of all caseswere tested and given correlation analysis. Results: The skin moisture of the LCH group were lower than that of the control group (P<0.05), and the TEWL and oil levels were higher than that of the control group (P<0.05). The positive rates of Lactobacillus (La) in the LCH group were lower than that in the control group (P<0.05), and the positive rates of Staphylococcus epidermidis (Se), Propionibacterium acnes (Pa), and Staphylococcus aureus (Sa) were higher than those in the control group (P<0.05). The positive rates of CD163 and ki-67 expression in the LCH group were 77.8 % and 52.8 %, respectively, which were higher than 19.4 % and 6.9 % in the control group (P<0.05). In the LCH group, Pearson correlation analysis showed there were positive correlation between skin moisture and Lactobacillus(P<0.05), TEWL, oil were positive correlated to the Staphylococcus epidermidis, Propionibacterium acnes, Staphylococcus aureu (P<0.05). Conclusion: The application of non-invasive skin barrier function detection in Langerhans cell histiocytosis can reflect the patient's skin moisture and oil status, and can also indirectly reflect the patient's skin microecology and immune function status. [ABSTRACT FROM AUTHOR]