The invention discloses a broad spectrum solar cell material and a preparation method thereof. The broad spectrum solar cell material is composed of the components in weight parts: 10-20 parts of graphite, 2-5 parts of silicon carbide, 3-8 parts of silicon nitride, 0.8-1.5 parts of erbium oxide, 2-8 parts of quantum dots, 20-30 parts of cyclopentene thiophene, 10-15 parts of diazosulfide, 2-5 parts of 1,8-octane dithiol, 0.15-0.55 part of lead hydroxide oxide sulfate, 1.5-8.5 parts of radical scavenger, 1-5 parts of thermal stabilizer, 3-10 ultraviolet light absorber and 1-3 parts of carbon black. The broad spectrum solar cell material has good electron stacking performance, higher carrier mobility and absorption peaks within the scope of 150-4000 nm, is capable of effectively improving the photoelectric conversion efficiency of solar cells and has broad application prospects.