Chronic periodontitis is a chronic inflammatory disease caused by plaque microorganisms, and removal of plaque and calculus is the gold standard for nonsurgical periodontal treatment. However, complete debridement is difficult, especially in some complex anatomical sites. Excessive scaling may result in the loss of healthy cementum and lead to dental hypersensitivity. Studies have shown that a diode laser can exhibit the best performance in an environment with blood because its wavelengths (630-1 064 nm) are close to the absorption peaks of heme and melanin and they have broad application prospects in the oral field. In nonsurgical periodontal treatment, diode lasers have three treatment modes: soft diode laser, antimicrobial photodynamic therapy and low-level laser therapy, which can be used alone or in combination. Although diode lasers cannot replace mechanical treatment to remove calculus, they can remove infected periodontal pocket epithelium, change the microcirculation to promote wound healing, reduce bleeding and relieve pain through photothermal effects and biological stimulation. The effect of diode laser treatment depends on the treatment dose. It is necessary to precisely control the output intensity and control the irradiation time to avoid thermal damage to the tissue. In the future, extensive research at the molecular level is needed to reveal the tissue response. At the same time, more high-quality, large-sample randomized controlled trials are needed to standardize the use of lasers for different stages and grades of periodontitis.