The invention discloses a shading device for a
greenhouse and a using method thereof, and belongs to the field of greenhouses. According to the shading device, a reflector is arranged to block solar rays, the temperature in the
greenhouse at
noon can be reduced, plants are prevented from withering and even dying due to a large amount of water loss, and an elastic shell is expanded by a large amount of heat generated by perpendicular incidence of the solar rays at
noon, so that the horizontal plane is raised, and
dynamic balance weight balls move upwards. Meanwhile, memory
metal sheets are deformed by heat so as to open openings in a
magnetism isolating cover to allow magnetic induction lines to pass through, so that
magnet balls generate upward attraction force on magnetic lifting ropes, and the reflector is gradually rotated from a vertical state to a horizontal state under the driving action of upward floating of the
dynamic balance weight balls so as to block light rays; After
sunlight deviates, along with heat dissipation, the
magnetism isolating cover is closed, so that the
magnet ball loses the
adsorption effect on the magnetic lifting
rope, the reflector is pulled back intothe containing groove under the
gravity effect of the
dynamic balance weight ball, and normal
photosynthesis of plants is guaranteed.