The invention discloses a heat transfer medium special for a solar heat pump and a preparation method thereof, which belong to renewable energy source utilization technology. The heat transfer medium is prepared by mixing, heating and stirring ethylene glycol, ionized water, triethanolamine, sodium dihydrogen phosphate, sodium benzoate, phosphoric acid, tolyltriazole styrene, borax, a defoaming agent, an inhibitor and a color concentrate in different weight ratios. The transfer medium has the characteristics of low freezing point, freeze prevention, high low-temperature flowing property, high boiling point, low evaporation loss, high specific heat, high heat conductivity, less foam, high anti-foam performance, and good anti-rust protection and descaling functions for metal pipelines.