Objective ·To explore the role of miR-128-3p/leptin (LEP) axis in the proliferation and inflammation of keratinocytes in psoriasis. Methods ·BALB/c mice were randomly divided into a control group (n=10) and a model group (n=10). Mice in the model group were given imiquimod on the back. miR-128-3p overexpression and interference plasmids, as well as LEP interference plasmids, were constructed and transfected into HaCaT cells, respectively. miR-128-3p and LEP mRNA were quantified by real-time quantitative polymerase chain reaction, and LEPprotein levels were detected by using Western blotting. Enzyme-linked immunosorbent assay was used to measure the content of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in the culture medium. MTT assay was used to evaluate cell activity and EdU assay was to used to test cell proliferation. The binding site between miR-128-3p and LEP was determined by using a dual luciferase reporter gene assay. Results ·Compared with mice in the control group, mice in the model group showed downregulated expression of miR-128-3p and upregulated expression of LEP at both RNA and protein levels (all P<0.05). The dual luciferase reporter gene assay confirmed that LEP was a downstream target of miR-128-3p. Compared with the negative control mimic (NC mimic) group, expression of miR-128-3p was up-regulated in the miR-128-3p mimic group, and expression of LEP was reduced. The levles of TNF-α, IL-6, and IL-1β were significantly lower in the miR-128-3p mimic group than in the NC mimic group. The relative cell viability and EdU-positive cell rate were also reduced after miR-128-3p up-regulation (all P<0.05). Compared with the negative control inhibitor (NC inhibitor) group, expression of miR-128-3p was down-regulated in the miR-128-3p inhibitor group, and expression of LEP was increased. The levles of TNF-α, IL-1β and IL-6 were increased after miR-128-3pdownregulation. miR-128-3p down-regulation led to an increase in relative cell viability and EdU-positive cell rate (all P<0.05). Further experimental results showed that LEP expression was up-regulated in the miR-128-3p inhibitor+LEP inhibitor group compared with that in the LEP inhibitor group, whereas the levels of TNF-α, IL-6, and IL-1β were elevated, and the relative viability of the cells and the rate of EdU-positive cells were increased (all P<0.05). Conclusion ·miR-128-3p downregulates LEP to inhibit the proliferation and inflammatory response of keratinocytes, thereby inhibiting the occurrence and development of psoriasis.