The invention discloses an automatic leveling device and a leveling method of a high-precision upright air-floating rotary platform, belongs to the technical field of rotary platform leveling, and aims to solve the problem that the interference moment index of a rotary platform can be affected as the gravity center of an upright air-floating rotary platform rotating component deviates from a rotation axis. An effective load is fixedly connected with a load mounting disc of the device; an air-floating shaft is connected with the lower surface of the load mounting disc; the air-floating shaft is correspondingly arranged in the center of the upper surface of an air-floating rotary platform main body; the bottom surface of the air-floating rotary platform main body is fixedly connected with an air-floating rotary platform base; the air-floating rotary platform base is supported by using an air-floating rotary platform height adjusting support; an x-axis leveling motor and a y-axis leveling motor are used for leveling the device by adjusting corresponding counterweight blocks. According to the leveling method, by adjusting one air-floating rotary platform height adjusting support, the corresponding position of the load mounting disc is the lowest point in a horizontal direction, a present rotary platform inclination angle can be measured, the straight line position of the present gravity center of the load mounting disc can be measured, and the moving distance of the counterweight block can be further obtained. The automatic leveling device and the leveling method are applied to automatic leveling of the rotary platform.