The invention relates to the technical field of chemical battery fuels, in particular to a metal-air battery. The metal-air battery comprises a housing, a metal positive electrode, an air negative electrode and an electrolyte solution cavity, wherein a baffle with a hole in the middle is arranged in the housing and used for dividing the electrolyte solution cavity into an upper electrolyte solution cavity and a lower electrolyte solution cavity; the upper electrolyte solution cavity is formed between the metal positive electrode and the air negative electrode; the metal positive electrode is cylindrical and the lower end of the metal positive electrode is opposite to the hole of the baffle; the air negative electrode surrounds the metal positive electrode, the lower end of the air negative electrode is connected with the baffle, and the outer side of the air negative electrode is connected with an oxygen selective membrane; and a filling hole communicated with the upper electrolyte solution cavity is formed in the top of the housing, a liquid discharge hole with a seal cover is arranged at the bottom, and one end of the seal cover is connected with a metal oxide adsorption strip. According to the metal-air battery, deposits on the surface of the positive electrode are easily removed, an electrolyte solution is easily replaced, the use is convenient, the maintenance period is short, and the redox rate is relatively high.