Diabetic foot (DF) is among the most serious complications of type 2 diabetes. DF infection (DFI) is a key factor in the deterioration and development of DF, so controlling infection plays an important role in the treatment of the disease. Traditional Chinese medicine foot bath has been widely used in China as a complementary and alternative therapy to improve circulation and infection control of DF. However, the existing evidence shows that its efficacy and safety are still insufficient. We report a study protocol about a multicenter, double-blind, randomized, placebo controlled trial which aims to make well-designed clinical trials to evaluate the efficacy and safety of herbal medicine foot bath decoction (FBD) and explore the mechanism of external washing of Chinese herbs in DFI.This study is a multicenter, double-blind, randomized, placebo controlled clinical trial in which 60 eligible participants were randomly divided into an experimental group and control group at a 1:2 ratio. Both groups received the same basic treatment for DF disease, the experimental group used FBD and ordinary dressing changes, while half of the patients in the control group received placebo and ordinary dressings, and the other half received placebo and silver ion dressings. Patients in both groups will be evaluated weekly for efficacy during the intervention. The primary efficacy indicators include the types of wound pathogens, interleukin 6 and tumor necrosis factor α. Secondary efficacy indicators included blood glucose, blood lipids, wound area, lower extremity blood vessel diameter, blood flow speed, walking speed, walking distance, and traditional Chinese medicine syndrome scores. We will also conduct a safety evaluation of the drug at the end of the trial.This multicenter, double-blind, randomized, placebo clinical trial not only provides data on the efficacy and safety of FBD, but also provides a novel treatment strategy for clinicians and DF patients.