Objective: To explore the protective effect and the underlying mechanism of Hu- Lu-Ba-Wan ( HLBW) on the testis of diabetic rats. Methods: Twenty-four male Wistar rats (160-180 g) were randomly divided into 3 groups according to a random number table,including a control group ( n= 8), diabetic group ( n= 8), and HLBW group ( n= 8). Diabetic rat model was established by high-fat-diet administration and single intravenous injection of streptozotocin (26 mg/kg). Then HLBW granule was administrated for 12 weeks. Fasting blood glucose and insulin levels as well as serum total testosterone level and testicular testosterone content were examined. Oxidative stress markers in both serum and testis were tested. Meanwhile, testicular morphology was observed under hematoxylin and eosin (HE) and the ultrastructure of Leydig cell was observed by electron microscope. The superoxide anion level was detected by DHE, and TUNEL-positive cells of testis was evaluated by TUNEL assay. The gene and protein expression of protein kinase C (PKCa), phosphorylated PKCa (P-PKCa) and P47phox in testicular tissues were determined by quantitative RT-PCR analysis and Western bolt analysis. Results: Compared with the diabetic group, HLBW treatment significantly reduced the fasting glucose levels and increased the levels of fasting insulin and testosterone in serum ( P< 0.01). HLBW administration also reduced the levels of reactive oxygen species (ROS) in plasma and alleviated the damage of oxidative stress in the testis of diabetic rats. Additionally, HLBW down-regulated the protein and mRNA levels of PKCa, P-PKCa and P47phox in testicular tissues. Conclusion: HLBW may attenuate the oxidative stress in the testis of diabetic rats via PKCa /NAPDH oxidase signaling pathway.