The invention discloses a multifunctional antibacterial mouthwash, which comprises a bacteriostatic agents, an anti-allergic agent, a cleaning agent, a odor remover, a sweetener, a sour agent and double distilled water. The invention also discloses a preparation method of the multifunctional antibacterial mouthwash. The method is as below: taking an appropriate amount of double distilled water, according to the amount adding polyhexamethylene biguanidine hydrochloride, strontium chloride, sodium dodecylsulphate, cyclodextrin and fruity flavor, stirring to dissolve the materials, and heating to 50 DEG C and maintaining for 60 min; adding aspartame, citric acid and sodium citrate, adjusting the pH value to keep the pH value at 6-7 to obtain the mouthwash. The mouthwash provided by the invention is comfortable in the mouth, contains teeth-cleaning ingredients that can effectively clean the teeth stains, and can make the teeth white and healthy. The mouthwash has strong inhibitory effect on Escherichia coli, Staphylococcus aureus and Candida albicans, and effectively prevents and treats oral bacteria proliferation, and reduces the incidence of oral disorder.