Objective We investigated the effects of barbaloin on podocyte function and on the nicotinamide adenine dinucleotide phosphate oxidase 4 (NEX4)/reactive oxygen species (ROS)/p38 mitogen activated protein kinase signaling pathway (p38 MAPK) in rats with diabetic nephropathy (DN). Methods The rats were fed high-sugar and high-fat diet for 4 weeks and injected 40 mg/kg STZ intraperitoneally establisha a DN rat model and randomly divided into a model group, a positive control group, dose dependent (low, medium, and high) experimental groups, and a normal group in which the rats were not treated. The positive control group was given 9.45 mg gliguidone per kilogram per day (kg·d) for six weeks. The low, medium, and high dose experimental groups were given 10, 20, and 40 mg/(kg·d) barbaloin, respectively, by gavage for six weeks. The normal group and model group were given equal volume distilled water by gavage for six weeks. Fasting blood glucose levels were measured using a blood glucose meter, and the levels of interleukin-1β (IL-1β) and serum tumor necrosis factor-α (TNF-α) were detected by enzyme-linked immunosorbent assay (ELISA). Hematoxylin and eosin (HE) staining was used to observe renal morphology. The levels of superoxide dismutase (SOD), malondialdehyde (MDA), and reactive oxygen species (ROS) in kidney tissue were detected using commercial SOD, MDA and ROS assay kits; and the levels of NADPH oxidase 4 (NOX4), p38 mitogen-activated protein kinase (MAPK), phospho-p38 MAPK, the glomerular podocyte gap transmembrane protein Nephrin, and Podocin were detected by western blot. Results Before administration, compared with the normal group, the fasting blood glucose level of the model group, the positive control group, and the low, medium, and high dose experimental groups increased (P <0. 05). After administration, glomerular hypertrophy, mesangial thickening, glomerular basement membrane thickening, and interstitial inflammatory infiltration were observed in the model group. In the low and middle dose group, glomerular hypertrophy was relieved gradually, the mesangial hyperplasia was mild to moderate, and the dilation of renal tubules was slowed down. In the high dose experimental group, the renal tissue was normal in morphology and clear in structure, and the shapes of the glomerulus and renal tubules were regular. Compared with the normal group, the levels of fasting blood glucose, and IL-1β, serum TNF-α, MDA, ROS, NOX4, and phospho-p38 MAPK proteins in kidney tissue of the model group increased (P < 0. 05), and the levels of SOD, SOD/ MDA, Nephrin, and Podocin proteins in kidney tissue decreased (P <0. 05). Compared with the model group, the levels of fasting blood glucose, and IL-1β, serum TNF-α, MDA, ROS, NOX4, and phospho-p38 MAPK proteins in kidney tissue of the positive control group and high dose experimental group decreased (P < 0. 05); and the levels of SOD, SOD/MDA, Nephrin, and Podocin proteins in kidney tissue increased (P <0. 05). The levels of fasting blood glucose, and IL-1β, serum TNF-α, MDA, ROS, and NOX4 proteins in kidney tissue of the middle dose experimental group decreased (P < 0. 05); and the levels of SOD, SOD/ MDA, Nephrin, and Podocin proteins in kidney tissue increased (P < 0. 05). The levels of fasting blood glucose, and IL-1β, serum TNF-α, MDA, and NOX4 proteins in kidney tissue of the low dose experimental group decreased (P <0. 05); and the level of SOD in kidney tissue increased (P < 0. 05). Compared with that before administration, the fasting blood glucose level of the positive control group, and the experimental (low, medium, and high dose) groups decreased after administration (P <0. 05). Conclusions Barbaloin can inhibit the NOX4/ROS/p38 signaling pathway to achieve anti-inflammatory actions and podocyte recovery.