The invention discloses a terrestrial heat pump combined drying device which comprises a drying tank, a terrestrial heat deep well, an evaporator I, an evaporator II and a circulating fan, wherein a plurality of layers of shelves are arranged in the drying tank; a plurality of penetrating holes are uniformly formed in the shelves; the shelves are equipped with hollow interlayers; baffle plates arearranged in the hollow interlayers; the shelves mutually communicate through a hollow main shaft; a hot air branch pipe is arranged above each shelf; and a plurality of air outlet holes are uniformlyformed in the pipe wall of each hot air branch pipe. In the early period, negative pressure is formed inside the drying tank through the circulating fan, thereby being beneficial to the drying of a material under hot water; through the baffle plates, the flowing path of the hot water in the shelves is lengthened, so that the effect of heat exchange between the hot water and the to-be-dried material can be enhanced; in the middle and later periods of drying, a heat pump hot air drying method is adopted; and by adoption of the heat pump hot air drying method, the condensation heat release amount of water vapor and the heat of fresh air during the low-temperature and negative-pressure drying process in the early period can be recycled, the energy utilization efficiency can be improved, and the material drying time can be shortened.