The present invention discloses an automatic magnetic buckle, which comprises a matching clamping head and a buckle base. The said clamping head comprises a clamping head housing, and the said clamping head housing has a cavity extending through the upper and lower ends of the clamping head housing. The said cavity is set with a buckle subassembly, the said buckle base is set with a clamping head matching with the said buckle subassembly, and the said clamping head and the buckle base are set with magnetic subassemblies which are mutually attracted. Clamping head and buckle base are attracted together through the matching of the magnetic subassembly. The buckle subassembly is matched with the clamping head to securely connect the clamping head and the buckle base. The present invention also discloses a method of using the automatic magnetic buckle.