The utility model relates to a low temperature heat pump drying system in portable. Include: one set of heat pump set, a frequency conversion axial fan, a circulating fan, wherein heat pump set comprises a compressor, an evaporimeter, a condenser, an auxiliary condenser, a bypass valve, an expansion valve, a drier -filter and a liquid storage pot, circulating fan is located in the middle of heat pump set condenser and the evaporimeter, the frequency conversion axial fan install on auxiliary condenser for auxiliary condenser's compulsory convection heat dissipation, this low temperature heat pump drying system in portable has modularization, portable, characteristics such as the system simple, simple, the energy -conserving high efficiency of accuse temperature, safe and reliable, one set and both can be used for the drying plant, can regard as the supplementary drying equipment that natural wind dry material is dry again. The applicable dry production process that has the same drying technology and similar drying condition in food drying etc. Of this low temperature heat pump drying system in portable.