The invention belongs to the technical field of battery manufacturing, and discloses a vacuum sealing method of a battery. According to the method, a battery to be sealed is placed in a vacuum environment of (-40)-(-60) KPa for at least 5 minutes and then is sealed, thus, gas in the battery can be enabled to be completely discharged on the premise that an electrolyte is not pumped out of the battery, highly-uniform pressure in the battery can be maintained, the retention quantity of the electrolyte in the battery is increased, the capacity of the battery is ensured, the service lifetime of thebattery is ensured, and meanwhile, the shape of the battery also can be enabled not to be changed. Moreover, the method is reasonable in process parameter setting, the environmental influence can beeffectively reduced in the vacuum environment, the method is simple and convenient to operate, the sealed environment can be rapidly optimized, the method is suitable for mass production, and a basisis provided for sealing a single battery as well as the product quality requirement is ensured.