The invention discloses a photo-thermal cooperatively controllably degradable mulch film and a preparation method thereof. The mulch film comprises the components in parts by weight: 85-95 parts of polyethylene, 1-5 parts of a photo-thermal sensitive catalyst, 5-10 parts of a plasticizer, 0.5-3 parts of a compatibilizer and 0.5-2 parts of an anti-oxidant. The preparation method comprises: mixing metal oxides and grinding into 60 meshes, processing in a muffle furnace at a high temperature for 2 h, blending with RuO2, grinding into 80 meshes to obtain the photo-thermal sensitive catalyst, then performing batching on polyethylene, the photo-thermal sensitive catalyst, the plasticizer, the compatibilizer and the anti-oxidant according to a weight ratio, mixing at a high speed and performing blow molding to obtain the mulch film. The mulch film possesses the mechanical properties and the application scope of conventional plastic mulch film, and is controllably environmental degradable and is capable of satisfying the usage requirements.