The invention discloses an outdoor projection device which comprises a heliostat, a Fresnel lens installed on an outdoor supporting body, and a rotating shaft. A condensation photovoltaic cell panel,a projection unit and a converting mechanism are arranged on the rotating shaft. The outdoor projection device further comprises an energy storage device and a cooling device which are connected withthe condensation photovoltaic cell panel and the projection unit. The projection unit comprises a light source and a lantern slide opposite to the light source and containing projection information. The geometric center of the condensation photovoltaic cell panel and the geometric center of the lantern slide both coincide with the focal point of the Fresnel lens. The converting mechanism is used for conversion between the condensation photovoltaic cell panel and the lantern slide. The Fresnel lens is used for receiving solar light reflected by the heliostat and then perpendicularly entering when being opposite to the condensation photovoltaic cell panel and is used for amplifying and imaging the projection information when being opposite to the projection unit. By means of the technical scheme, the energy consumption of outdoor advertisements can be reduced, light pollution and environmental pollution are reduced, and replacement is easy.