The invention discloses a safety protection device for a solar heat exchanging system, which comprises circular tubes and rotary mechanisms arranged coaxially outside a plurality of vacuum heat connecting tubes one by one. One half surface of the circular tube from top to bottom is transparent while the other half from top to bottom is embellished with colours. Both ends of the circular tube contact the bottom of a header and the upper part of a bracket rotatably. The rotary mechanism comprises gears which are same in quantity with the circular tubes, a slide block, a slide block driving mechanism and a machine-electricity controller. The gears and circular tubes are integrally formed and arranged at the upper parts of the circular tubes. The surface of the slide block opposite to the gear is provided with teeth which can be meshed with the gears. The slide block is installed on the front end surface of the header via the slide block driving mechanism so that the slide block moves to mesh with the circular tubes in sequence and drive the circular tubes to rotate at an effective angle. The safety protection device can reduce or close the vacuum tube which absorbs the solar energy according to the solar radiation intensity and temperature of the system.