A hydrogen-helium mixed gas aerostat comprises a positioning plate. Inclined photographing equipment is arranged below the positioning plate, a mixed gas controller is arranged above the positioning plate, an inert gas controller is arranged above the mixed gas controller, a balloon sleeving the mixed gas controller is a mixed balloon, a balloon sleeving the inert gas controller is an inert balloon which is positioned inside the mixed balloon, the inert balloon and the mixed balloon are inflated respectively through inflation ports and communicated with a mixed gas outlet and an inert gas outlet respectively, inert gas in the inert balloon can be discharged into the mixed balloon through the inert gas outlet, mixed gas in the mixed balloon can be discharged through the mixed gas outlet, and opening and closing of the mixed gas outlet and the inert gas outlet are respectively controlled by the mixed gas controller and the inert gas controller. The hydrogen-helium mixed gas aerostat is supportive of multi-angle high-low photographing switching and low in cost.