The invention belongs to the technical field of molecular biology detection. Specifically, the application provides a magnetic bead method saliva DNA extraction kit that only needs one-step washing, which includes a lysis solution, a binding solution, a proteinase K solution, a washing solution and an elution solution. buffer. A saliva DNA extraction kit includes lysing solution, binding solution, proteinase K solution, washing solution and elution buffer. The lysate contains Tris, EDTA, NaCl, NaDC, dodecyl-N-betaine, NLS, GuHCl, TritonX100, NH 4 Cl, mercaptoethanol; binding solution including isopropanol, PEG 8000, Brij 58; washing solution including GuHCl, Tris, ethanol, sodium bicarbonate; elution buffer including Tris, EDTA. In the present application, by preparing a washing solution containing a relatively high concentration of sodium bicarbonate (slightly stronger than sodium acetate and sodium chloride), the ion balance and the effect of providing alkalinity are taken into account at the same time, and a zwitterionic detergent is used in combination. Alkyl-N-betaine, a magnetic bead-based saliva DNA extraction kit was constructed that only required one-step washing.