Near space aerostat and control method thereof

The invention discloses a near space aerostat and a control method thereof. The aerostat comprises a carrying ball, a protection ball, a flat floating carrier ball and a load, the flat floating carrier ball is arranged in the protection ball, the flat floating carrier ball and the protection ball are connected with the load located on the lower side at the same time, and the carrying ball is connected with the upper side of the protection ball; and a separating device for cutting off the connection is arranged between the carrying ball and the protection ball. Appropriate buoyancy gas is filled into the flat floating ball by utilizing a net lifting force empirical formula, the flat floating ball is released in the daytime, the flat floating ball system is protected and isolated from sunlight and ozone through an outer balloon, the flat floating system is brought to a specified height for flat floating in a string ball carrying mode, day-night conversion of an aerostat carrier is realized through a cabin throw